conference low energy antiproton...
TRANSCRIPT
CONFERENCELOW ENERGY ANTIPROTON
PHYSICSMars 12 - 16th 2018
Sorbonne Universite, Jussieu Campus,Paris-France
Organizers
• Paul Indelicato, Laboratoire Kastler Brossel, Sorbonne universite
• Laurent Hilico, Laboratoire Kastler Brossel, Sorbonne universite
• Patrice Perez, CEA-Irfu
• Yves Sacquin, CEA-Irfu
• Philippe Briet, CEA-Irfu
Contact : [email protected]
Proceedings
The proceedings will be published in Hyperfine Interaction. The paper from LEAP 2018,once accepted will appear immediately on the journal. There will be a separate topicalcollection that will regroup all papers from LEAP.
The papers will be freely available for one year, and then will require a regular sub-scription to the journal. There will be no paper copies provided.
More info on http://leap2018.lkb.upmc.fr/
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Welcomedrinkand
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Welcome:
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16:00-16
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16:20-16
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16:00-16
:20:Edm
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16:20-16
:40:TakashiHiguchi
16:40-17
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Contents
Talks 8
1 Peter von Ballmoos, Antimatter in Space 9
2 Zhi-Cheng Tang, Antiproton Flux and Antiproton-to-Proton Flux Ratioin Primary Cosmic Rays Measured with the AMS on ISS 10
3 Gabriel Chardin, Gravity and Antimatter 11
4 Giovanni Manfredi, Cosmological structure formation with negative mass 12
5 Arnaldo J. Vargas, CPT violation, Lorentz violation, and low-energyantiprotons 13
6 Stephan Ulmer, The BASE Collaboration Review and Outlook 14
7 Christian Smorra, A ppb measurement of the antiproton magnetic mo-ment 15
8 Christian Carli, ELENA 16
9 Eberhard Widmann, Prospects of FLAIR, the Facility for Low-energyAntiproton and Ion Research 17
10 Manuel Vogel, The HITRAP facility for deceleration and trapping ofhighly charged ions and antiprotons 18
11 Alexandre Obertelli, PUMA: a trap project for antiprotons and short-lived nuclei 21
12 Dieter Grzonka, Search for polarized antiproton production 22
13 Ghanshyambhai Khatri, ATRAP Experiment 23
14 Naofumi Kuroda, ASACUSA CUSP antihydrogen beam experiment 24
15 Chris Ø. Rasmussen, 1S-2S Spectroscopy of Antihydrogen in the AL-PHA Experiment 25
16 Daniel Krasnicky, The AEGIS Antimatter Gravity Experiment 26
17 Bruno Mansoulie, Status of the GBAR experiment at CERN 27
18 William Bertsche, Measuring antimatter gravitation with trapped anti-hydrogen: The ALPHA-g experiment 28
19 Chole Malbrunot, New in-beam measurement of the hydrogen hyperfinesplitting and prospects 29
20 Kai Nordlund, Nuclear stopping power of antiprotons 31
3
21 Andrey I. Bondarev, Differential cross sections in collisions of low-energy antiprotons with ions and atoms 32
22 Alban Kellerbauer, Laser cooling of anions for ultracold antihydrogen 33
23 Sebastian Wolf, Cooling of mixed ion crystals for GBAR 34
24 Daniel Martinez Zambrano, Lyman-α source for laser cooling antihy-drogen 35
25 Nicola Zurlo, Antihydrogen formation via charge exchange betweenpositronium and antiproton 36
26 Angela Gligorova, A new approach for measuring antiproton annihila-tion at rest with Timepix3 37
27 Egle Tomasi-Gustafsson, The PANDA experiment at FAIR 38
28 Elena Vannuccini, GAPS, low-energy antimatter for indirect dark-mattersearch 39
29 Bernadette Kolbinger, A Detector for Measuring the Ground State Hy-perfine Splitting of Antihydrogen 40
30 Edmund G. Myers, Testing CPT with the Anti-hydrogen Molecular Ion 41
31 Takashi Higuchi, Toward an improved comparison of the proton-to-antiproton charge-to-mass ratio 42
32 Nodoka Yamanaka, Electric dipole moment of light nuclei 43
33 Alisher Kadyrov, Low-energy antiproton scattering 45
34 Marianne Dufour, Ab-initio calculations of reactions involving the 3-body system (p, e+, e−) between the e− + H(n = 2) and e− + H(n = 3) 46
35 Piotr Froelich, Four-body treatment of the antihydrogen-positroniumsystem: binding, structure, resonant states and collisions 47
36 Silvia Masciocchi, Production of light (anti-)(hyper-)nucleiin heavy-ion collisions 48
37 Alberto M. Alonso, Guiding and manipulating Rydberg positroniumusing inhomogeneous electric fields 49
38 Pavel Moskal, Tests of discrete symmetries in positronium decays withthe J-PET detector 50
39 Akira Ishida, Recent progress in positronium experiments for Bose-Einstein condensation 51
4
40 Timothy Friesen, Observation of the hyperfine spectrum of antihydro-gen 52
41 Takamasa Momose, Spectroscopy of the 1S−2P transition of antihydro-gen 53
42 Juhi Raj, Study of time reversal symmetry in the decay of Ortho-Positronium atoms using J-PET 54
43 Welsch Carsten, Accelerators Validating Antimatter Physics 55
44 Sandrine Emery-Schrenk, Recent BABAR results on CP violation 57
45 Masaki Hori, Single-photon laser spectroscopy of cold antiprotonic he-lium 58
46 Valery V. Nesvizhevsky, Constraints for fundamental short-range forcesfrom the neutron whispering gallery, and extention of this method toatoms and antiatoms 59
47 Julian Fesel, Laser cooled anions as a sympathetic coolant for antipro-tons 60
48 Paolo Crivelli, Positronium and Muonium two photon laser spectroscopy 61
49 Anna Soter, Production of cold muonium for future atomic physics andgravity experiments 62
Posters 64
1 Johann Marton, High sensitivity search for Pauli-forbidden atomic tran-sitions at the LNGS underground laboratory 65
2 Francois Butin, AD infrastructures and experimental areas evolutionsin the context of ELENA development 66
3 Valeriy I.Nazaruk, Models of nn transition in medium 67
4 Eigo Shintani, Proton and neutron electromagnetic form factor andcharge radius in lattice QCD 68
5 Minori Tajima, Status of antihydrogen production towards cold andintense atomic beams in ASACUSA 69
6 Kevin Leveque, Charge exchange three-body reaction in the presenceof a laser field 70
7 Sergey Vasiliev, Gravitational and matter-wave spectroscopy of atomichydrogen at ultra-low energies 71
5
8 Bianca Veglia, Beam Emittance Studies of Electron Cooling in ELENA 72
9 Bongho.H. Kim, Development of TOF detector in GBAR experiment 73
10 Juan M. Cornejo, Towards sympathetic cooling and manipulation ofsingle (anti-)protons by atomic ions in a double-well Penning trap 74
11 Kamil Dulski, Positronium decay study with the J-PET detector 75
12 Mattia Fanı, Detection of charged particle, non neutral plasma, antihy-drogen and positronium in AEgIS 76
13 Mykola V. Maksyuta, ON THE POSSIBILITY OF FORMATION OFEXOTIC PARTICLES AT THE CHANNELING OF LOW ENERGYANTIPROTONS IN LiH CRYSTAL 77
14 Mykola V. Maksyuta, DESCRIPTION OF THE TRANSMUTATIONOF ELEMENTARY PARTICLES USING THE THEORY OF KNOTS 78
15 Volodymyr Rodin, Realistic 3D implementation of electrostatic elementsfor low energy machines 79
16 Barbara Latacz, High intensity positron beam production for the GBARexperiment 80
17 Louvradoux Thomas,Sympathetic cooling of H+. 81
18 V. Mackel, 3D-imaging of antimatter annihilation using the ASACUSAMicromegas tracker 82
19 Pierre-Philippe Crepin, Casimir-Polder shifts on quantum levitationstates 83
20 Miguel Fernandes, Intensity measurement of the Antiproton Deceler-ator beam using a Cryogenic Current Comparator with nano-ampereresolution 84
21 Nikodem Krawczyk, Feasibility study of the measurement of annihila-tion photons polarization with the J-PET detector 85
22 Svante Jonsell, Simulations of the formation of trappable antihydrogen 86
23 Andrea Capra, Lifetime of Magnetically Trapped Antihydrogen in AL-PHA 87
24 N. Evetts, Magnetometry Techniques for Gravitational Measurementsof Antihydrogen with ALPHA-g 88
25 L. Martin, Development of the Radial Time Projection Chamber for theALPHA-g antimatter gravity experiment 89
6
26 Chukman So, Magnetic Trap Design in ALPHA-g 90
7
Talks
Monday 12th
8
1
Antimatter in Space
Peter von BallmoosInstitut de Recherche en Astrophysique et Planetologie9, avenue du Colonel Roche, 31028 Toulouse, France
Balloon and satellite experiments detect antimatter in the Universe both directly, asa cosmic ray component, and indirectly, through characteristic annihilation signatures.
Positrons: For over five decades positrons have been studied in cosmic rays, just aslong as we have been observing them through the 511 keV gamma-rays they emit whenannihilating. The question on their origin, however, is still far from being settled, neitherfor the high-energy cosmic ray positrons, nor for the positrons annihilating in the centralregions of our Galaxy. Nevertheless, the most plausible scenarios for their production allinvolve processes occurring at the endpoints of stellar evolution.
Baryonic antimatter: During forty years, direct detection of baryonic antimatter hasessentially concerned the measurement of antiprotons, naturally produced in cosmic rayinteractions with the interstellar medium. Recently, the tentative detection of a few3He by AMS has revitalized the discussion on the existence of baryonic antimatter in theUniverse. Since revoking an MeV bump hinted in the seventies, gamma-ray astronomy hasmore and more constrained the fraction of antimatter possibly contained in astrophysicalobjects. The absence of characteristic annihilation features on all scales has virtuallyruled out the existence of substantial quantities of antimatter in the visible Universe.
9
2
Antiproton Flux and Antiproton-to-Proton Flux
Ratio in Primary Cosmic Rays Measured with the
AMS on ISS
Zhi-Cheng Tang1
1. Institute of High Energy Physics, Chinese Academy of Sciences
Precision measurements by AMS of the antiproton flux and the antiproton-to-protonflux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV arepresented based on 3.49 × 105 antiproton events. At ∼20 GV the antiproton-to-protonflux ratio reaches a maximum. Unexpectedly, above 60 GV the antiproton spectral indexis consistent with the proton spectral index and the antiproton-to-proton flux ratio showsno rigidity dependence in the rigidity range from ∼60 to ∼500 GV. This unexpectedobservation requires new explanation of the origin of cosmic ray antiprotons.
10
3
Gravity and Antimatter
Gabriel ChardinCNRS/DGDS, 3 rue Michel-Ange, 75016 Paris
Can we expect a difference in the trajectories of particles and antiparticles in a gravita-tional field ? Surely, since the Equivalence Principle is central to General Relativity, itseems that any such difference must be vanishingly small in GTR. On the other hand,Scherk [1] showed that supergravity with N = 2-8 generators lead to antigravity. Usingarguments developed by Philip Morrison [3], Hermann Bondi [3], Richard Price [4], TsviPiran [5] and others, I will show that a simple modification of the expression of the Equiv-alence Principle would lead to antigravity, as observed in the analog system of electronsand holes in a semiconductor [6].
Also, using the recent demonstration that negative mass solutions are allowed in ade Sitter spacetime [7], I describe the counter-intuitive polarisation and levitation effectsthat occur in General Relativity when bound systems of positive mass and negative massparticles are considered [4]. This will lead us to the Dirac-Milne universe [8], a universethat, unlike the standard Λ-CDM model, and without any free parameter, is impressivelyconcordant, without requiring Dark Matter and Dark Energy. I will also briefly describethe three experiments at CERN, ALPHA-g, AEgIS and Gbar, aiming at the sensitivityof antigravity and beyond on antihydrogen atoms.
References
[1] J. Scherk, Phys. Lett. B 88, 265 (1979).[2] P. Morrison, Am. J. Phys. 26, 358 (1958).[3] H. Bondi, Rev. Mod. Phys. 29, 423 (1957).[4] R.H. Price, Am. J. Phys. 61, 216 (1993).[5] T. Piran, Gen. Rel. Grav., 29, 1363 (1997).[6] I.M. Tsidil?kovskii, Soviet Physics Uspekhi, 18, 161 (1975).[7] S. Mbarek and M.B. Paranjape, Phys. Rev. D 90, 101502 (2014).[8] A. Benoit-Levy and G. Chardin, A&A 537, A78 (2012).
11
4
Cosmological structure formation with negative mass
G. Manfredi1, J.-L. Rouet2, B. Miller3, G. Chardin4
1. Universite de Strasbourg, CNRS, IPCMS UMR 7504, F-67000 Strasbourg, France.2. Universite d’Orleans, CNRS/INSU, BRGM, ISTO, UMR7327, F-45071 Orleans, France.
3. Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129, USA.4. Centre National de la Recherche Scientifique, Rue Michel-Ange, 75016 Paris, France.
While cosmological structure formation with negative mass objects may seem initially strange, the pos-sibility that particles with negative mass exist has long been considered [1–3], starting from the seminalwork of H. Bondi [4]. More recently, Paranjape and Mbarek have shown that negative mass solutions areviable in a de Sitter universe [5]. Besides, we cannot but note the strangeness of the Standard Cosmo-logical Model, which – although impressively concordant on primordial nucleosynthesis, CMB, BAO andSN1a luminosity distance – features a very strange composition, with Dark Matter and Dark Energy, twounidentified components, supposedly representing approximately 96% of the Universe content.In this context, Benoit-Levy and Chardin [6] have recently proposed a symmetric matter-antimatteruniverse, analog of the electron-hole system in a semiconductor, where antimatter particles have a negativegravitational mass. The Dirac-Milne universe appears as gravitationally empty (or coasting) at largescales, and is remarkably concordant without any adjustable parameter.In order to explore such alternative cosmological scenarios, we construct a family of Newtonian non-relativistic models with equal amounts of negative and positive gravitational mass particles, which in-cludes as a special case the Dirac-Milne scenario. We perform N-body simulations of these negative-massmodels for an expanding one-dimensional universe and study the associated formation of gravitationalstructures, focusing in particular on the Dirac-Milne case. The differences and analogies with the standardcosmological model are highlighted and discussed.
References
[1] R. H. Price, American Journal of Physics 61, 216 (1993).[2] P. D. Mannheim, Found. Phys. 30, 709 (2000).[3] R. T. Hammond, Eur. J. Phys. 36, 025005 (2015).[4] H. Bondi, Rev. Mod. Phys. 29, 423 (1957).[5] S. Mbarek and M.B. Paranjape, Phys. Rev. D 90, 101502 (2014).[6] A. Benoit-Levy and G. Chardin, A&A 537, A78 (2012).
12
5
CPT violation, Lorentz violation, and low-energy
antiprotons
Arnaldo J. Vargas1
1. Department of Physics, Loyola University New Orleans, New Orleans, Louisiana 70118, USA
The Standard-Model Extension (SME) is an effective field theory that extends the standard model ofparticle physics and general relativity by incorporating Lorentz- and CPT-violating operators of arbitrarymass dimension. Experimental collaborations searching for deviations from CPT symmetry can benefitfrom using models derived from the SME. Using these models the experimental groups can identify thetype of CPT-violating terms they are testing, quantify their findings as bounds on these CPT-violatingoperators, and compare the sensitivity of their results with other experimental collaborations around theworld. In many cases the main experimental signal for CPT violation targeted by the collaborations is onlysensitive to a limited set of CPT-violating terms and with the help of the SME the experimental groups canidentify other experimental signals that are sensitive to different sets of CPT-violating terms maximizingthe impact of their experiment. The SME models also indicate that the if CPT symmetry is brokenthen it is possible for signals for Lorentz violation to be enhanced in antimatter experiments comparedto ordinary matter experiments. This observation suggests that antimatter experiments could lead to abetter understanding of gravity at the quantum level because Lorentz violation is considered a possiblelow-energy signal for candidate quantum gravity theories. In this talk the main features of SME models fordifferent experimental scenarios such as antimatter spectroscopy experiments, antiproton Penning-trapexperiments, muon spin-precession experiments, and antimatter gravity tests will be discussed.
13
6
The BASE Collaboration Review and Outlook
S. Ulmer1, A. Mooser1, C. Smorra1,2, S. Sellner1, M. Bohman1,3,M. J. Borchert1,4, J. A. Harrington3, T. Higuchi1,5, G.
Schneider1,6, M. Wiesinger1,3, K. Blaum3, Y. Matsuda5, C.Ospelkaus4, W. Quint7, J. Walz6,8, Y. Yamazaki1
1 RIKEN, Ulmer Fundamental Symmetries Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan,2 CERN, 1211 Geneva, Switzerland, 3 Max-Planck-Institut fur Kernphysik, Saupfercheckweg 1, D-69117Heidelberg, Germany, 4 Leibnitz Universitat, Welfengarten 1, D-30167 Hannover, Germany, 5 Graduate
School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan, 6 Institut fur Physik,Johannes Gutenberg-Universitat D-55099 Mainz, Germany, 7 GSI Helmholtzzentrum fur
Schwerionenforschung GmbH, D-64291 Darmstadt, Germany, 8 Helmholtz-Institut Mainz, D-55099Mainz, Germany
The Baryon Antibaryon Symmetry Experiment (BASE-CERN) at CERNs antiproton decelerator facilityis aiming at high-precision comparisons of the fundamental properties of protons and antiprotons, suchas charge-to-mass ratios, magnetic moments and lifetimes. Our single-particle multi-Penning-trap experi-ments provide sensitive tests of the fundamental charge-parity-time invariance in the baryon sector. BASEwas approved in 2013 and has measured since then the antiproton-to-proton charge-to-mass ratio with afractional precision of 69 p.p.t. [1], as well as the antiproton magnetic moment with fractional precisionsof 0.8 p.p.m. [2] and 1.5 p.p.b. [3], respectively. At our matter companion experiment BASE-Mainz,we have performed proton magnetic moment measurements with fractional uncertainties of 3.3 p.p.b. [4]and 0.3 p.p.b. [5]. By combining the data of both experiments we provide a baryon-magnetic-momentbased CPT test
gp/2
gp/2= 1.000 000 000 2(15), (1)
which improves the uncertainty of previous experiments [6] by more than a factor of 3000. A uniqueantiproton reservoir trap used in BASE furthermore allows us to set constraints on directly measuredantiproton lifetime [7]. Our current value τp > 10.2 a improves previous best limits by a factor of 30. Inthis talk I will review the achievements of BASE and focus on recent developments which will allow usto further reduce our measurement uncertainties.
[1] S. Ulmer et al., Nature 524, 196 (2015)[2] H. Nagahama et al., Nat. Commun. 8, 14084 (2017)[3] C. Smorra et al., Nature 550, 371 (2017).[4] A. Mooser et al., Nature 509, 596 (2017) (2014).[5] G. Schneider et al., Science 358, 1081 (2017).[6] J. DiSciacca et al., Phys. Rev. Lett. 110, 130801 (2013).[7] S. Sellner et al., New. J. Phys. 19, 083023 (2017).
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A ppb measurement of the antiproton magnetic
moment
C. Smorra1 on behalf of the BASE collaboration1. RIKEN, Ulmer Fundamental Symmetries Laboratory, 2-1 Hirosawa, Wako-shi, Saitama, JAPAN,
351-0198
The high-precision comparisons of proton/antiproton properties carried out in the advanced multi Penning-trap system of the BASE experiment challenge the CPT symmetry in the Standard Model of particlephysics, since any deviation in proton and antiproton properties would hint to yet uncovered CPT-oddinteractions that would act differently on matter and antimatter-conjugates.We recently reported a measurement of the antiproton magnetic moment with 350-fold improved precision[1, 2]. To this end, we store single antiprotons in a multi-Penning trap system and measure the frequencyratio of the Larmor frequency to the cyclotron frequency, the frequency ratio providing the magneticmoment of the antiproton in units of the nuclear magneton. Our recent measurement uses a novel multi-trap two-particle scheme, which enhances the data accumulation rate compared to the established double-trap method. We use one particle at about 350 K energy in the radial modes to measure the cyclotronfrequency and an ultra-cold particle with less than 200 mK energy for the detection of individual spin-transitions to probe the Larmor frequency. This method became possible by reducing parasitic energyfluctuations during the adiabatic transport of the Larmor particle to less than 22 mK per cycle. In thisway, we improved the relative uncertainty of the antiproton magnetic moment to 1.5 ppb uncertainty(68 % C.L.) [1]. The result is in agreement with our measurements of the proton magnetic moment [3, 4]and supports CPT invariance up to an energy resolution of 10−24 GeV.In my presentation, I will present the observation of individual antiproton spin transitions [5], which areabsolutely essential for multi-trap methods, and our latest multi-trap magnetic moment measurement [1].
-40 -20 0 20 400.0
0.1
0.2
0.3
0.4
0.5
(gp_-gp)/gp (in10-9)
Spin
-flip
pro
babilit
y
Figure 1: Spin-flip resonance of the antiproton g-factor measurement with 1.5 ppb resolution.
References
[1] C. Smorra et al. Nature 550, 371 (2017).[2] H. Nagahama et al., Nat. Commun. 8, 14084(2017).[3] A. Mooser et al. Nature 509, 596 (2014).[4] G. Schneider et al., Science 358, 1081 (2017).[5] C. Smorra et al., Phys. Lett. B 769, 1 (2017).
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ELENA
C. Carli1 on behalf of the AD and ELENA teams1. CERN
The CERN Antiproton Decelerator AD provides antiproton beams with a kinetic energy 5.3 MeV to anactive users community. The experiments typically capturing the antiprotons in traps would profit froma lower beam energy, as this would allow them to improve the capture efficiency. However, with thegiven AD circumference, it is not possible to significantly reduce the extraction energy of this machine.The Extra Low Energy Antiproton ring (ELENA) is a small synchrotron with a circumference of 30.4m, a factor 6 smaller than the AD, to further decelerate antiprotons from the AD from 5.3 MeV to100 keV. Controlled deceleration in a synchrotron equipped with an electron cooler to reduce emittancesin all three planes will allow the existing AD experiments to increase substantially their antiprotoncapture efficiencies and render new experiments possible. A status report on the ELENA project and,in particular, on progress of ring commissioning using 100 keV H− beams from an external source andantiprotons from the AD will be given.
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Prospects of FLAIR, the Facility for Low-energy
Antiproton and Ion Research
Eberhard Widmann1
1. Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3,1090 Vienna, Austria
With the construction of FAIR, the Facility for Antiproton and Ion Research at Darmstadt, gainingmomentum, it becomes timely to discuss again the opportunities for physics with low-energy antiprotonsat FAIR. FLAIR as defined in the Baseline Technical Report in 2005 [1] consisted of two storage rings,a magnetic Low-energy Storage Ring LSR and an electrostatic Ultra-low energy Storage Ring USR, andthe HITRAP facility. The core features of FLAIR are the simultaneous use of the facility for low-energyantiprotons and highly charged ions, and the availability of both fast and slow extracted antiprotons atenergies down to 20 keV as well as at rest in HITRAP.FLAIR, together with the NESR storage ring needed for deceleration, is not part of the phase 1 of FAIRand thus its realisation is currently unclear. Nevertheless, significant progress has been made in the meantime with CRYRING, which was selected as LSR by the FLAIR community, having been modified for itsusage as LSR, moved to GSI/FAIR and installed behind the existing Experimental Storage Ring ESR [2].Together with the HITRAP facility also starting operation at the ESR, two of the central componentsof FLAIR are now existing and will start the physics program with highly charged ions. A study wasmade how to bring antiprotons from the production target to the ESR in order to generate the fullFLAIR facility at the current location of ESR, CRYRING, and HITRAP. The study [3] concluded thatit is possible to transfer antiprotons to ESR and to decelerate them in ESR and CRYRING, producingantiproton beams of similar intensity and energy as will be available soon at CERN-AD/ELENA.The advantage of the availability of internal targets in the storage rings and slow extracted beams fromFLAIR makes several experiments uniquely possible at this facility. This talk will describe the physicspotential with low-energy antiprotons of FLAIR.
References
[1] FLAIR Technical Proposal (2005), available from http://flairatfair.eu/.[2] M. Lestinsky et al., Eur. Phys. Journ. 225, 797 (2016).[3] T. Katayama et al., Phys. Scripta T 166 014073 (2015).
17
10
The HITRAP facility for deceleration and trapping
of highly charged ions and antiprotons
M. Vogel1, Z. Andelkovic1, G. Birkl2, F. Herfurth1, H.-J. Kluge1,W. Nortershauser3, W. Quint1, Th. Stohlker1, R.C. Thompson4,
G. Vorobjev1, and the HITRAP collaboration1. GSI, Darmstadt, Germany
2. Institut fur Angewandte Physik, TU Darmstadt, Germany3. Institut fur Kernhysik, TU Darmstadt, Germany
4. Imperial College London, London, UK
The HITRAP facility at GSI, Darmstadt, Germany, is designed for deceleration and cooling of highlycharged ions from energies of several MeV to 4 K and subsequent low-energy transport to a number ofexperimental stations [1,2,3]. To this end, it features a series of deceleration stages and a cryogenicPenning trap in which the particles are cooled by electron cooling and resistive cooling. This talk willpresent the outline of the facility, its status, and briefly look at the Penning-trap experiments ARTEMIS,SPECTRAP and HILITE currently located at HITRAP. Also, possibilities for experiments with low-energy antiprotons in the framework of FAIR (Facility for Antiproton and Ion Research), currently underconstruction, will be discussed.
Figure 1: Schematic of the current HITRAP facility.
References
[1] H.-J. Kluge et al., HITRAP: A facility at GSI for highly charged ions, Advances in Quantum Chemistry53 (2007) 83.[2] Z. Andelkovic et al., HITRAP - a facility for experiments on heavy highly charged ions and onantiprotons, Journal of Physics: Conference Series 194 (2009) 142007.[3] Z. Andelkovic et al., Beamline for low-energy transport of highly charged ions at HITRAP, Nucl. Inst.Meth A 795 (2015) 109.
18
19
Talks
Tuesday 13th
20
11
PUMA: a trap project for antiprotons and
short-lived nuclei
Alexandre ObertelliInstitut fur Kernphysik
Technische Universitat Darmstadt
Antiprotons as probe for nuclear studies with short-lived isotopes remain unexploited despite past pioneerworks at CERN/LEAR and Brookhaven. Antiprotons offer a very unique sensitivity, as a probe, to theratio of neutron and proton densities at annihilation site, i.e. in the density tail of the nucleus. Theproject officially started on January 1st, 2018. Its motivations and concept will be presented.
21
12
Search for polarized antiproton production
D. Grzonka et al.Institut fur Kernphysik, Forschungszentrum Julich,
52425 Julich, Germany
Polarization observables allow the extraction of more detailed information of the structure of hadronsand their interaction and the disentangling of various reaction mechanisms is often only possible by aseparation of different spin configurations. For antiprotons possible methods for polarization are discussedsince the first antiproton beams became available [1] but up to now there is no simple procedure for thepreparation of a polarized antiproton beam. The actual favored solution is the spin filter method wherea stored unpolarized antiproton beam is polarized by passing through a polarized target. The techniquein principle works as shown with protons but it is rather effortful [2]. A quite simple procedure for thegeneration of a polarized antiproton beam could be worked out if antiprotons are produced with somepolarization.In order to investigate this possibility measurements of the polarization of produced antiprotons havebeen started at CERN. Secondary particles produced with the PS beam were transferred in a beamline adjusted to 3.5 GeV/c momentum to the detection system sketched in Fig.1. It included a liquidhydrogen analyzer target, tracking detectors, scintillators, a Cherenkov detector to veto the dominantpion background and a DIRC for the particle identification. The polarization will be determined from theasymmetry of the elastic antiproton scattering in the CNI region for which the analyzing power is wellknown. Details on the experiment and the ongoing data analysis are given in [3][4] and the referencescited therein.
DIRC
Scintillator- paddles
Drift- chamber
lH2- target
Beam
150 mrad
20 mrad (CNI)
Scint. fiber hodoscope
Drift- chamber Start-
scintillator
Cherenkov
Figure 1: Sketch of the detection system used for the antiproton polarization study.
References
[1] A. D. Krisch, AIP Conf. Proc. 145 (1986).[2] W. Augustyniak et al., Phys. Lett. B 718 64-69 (2012).[3] D. Alfs et al., Acta Phys. Pol. B 48 1983 (2017).[4] D. Grzonka et al., Acta Phys. Pol. B 46, 191 (2015).
22
13
ATRAP Experiment
Ghanshyambhai Khatri1,5, Eric Tardiff1,5, Gerald Gabrielse1,5,Bartosz Glowacz3, Dieter Grzonka4, Christopher Hamley1, EricHessels6, Nathan Jones1, Siu-Au Lee2, Tharon Morrison1, ColeMeisenhelder1, Edouard Nottet5, Cory Rasor2, Samuel Ronald2,
Cody Storry6, Richard Thai6, Dylan Yost2, Daniel MartinezZambrano5, Marcin Zielinski3
1. Department of Physics, Harvard University, Cambridge, MA 02138, USA2. Department of Physics, Colorado State University, Fort Collins, CO 80523, USA
3. Faculty of Physics, Astronomy, and Applied Computer Science, Jagiellonian University, 30-059Krakow, Poland
4. Forschungzentrum Juelich GmbH, D-52425, Juelich, Germany5. Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
6. Department of Physics and Astronomy, York University, Toronto, Ontario M3J 1P3, Canada
ATRAP, located at CERN’s Antiproton Decelerator (AD), is unique among the experiments at the AD- it has both octupole and quadrupole magnets in its nested Penning-Ioffe trap, it is a vertical apparatuswhere the antiprotons enter from the bottom of the apparatus and positrons enter from the top. Thepositrons are accumulated from a Na-22 source (located 6m away) and are guided through magnetictransfer lines to the trap. The pbar catching efficiency is increased with the help of a field boostingsolenoid (2.7T), which can be turned on and off in addition to the background 1T field, giving roughly100,000 antiprotons per shot and can get up to a few million by stacking several shots. Electron cloudsare used for cooling the antiprotons and positrons. ATRAP has four radial and an axial access ports forlaser cooling and spectroscopy of antihydrogen, a Cesium oven for increasing the antihydrogen productionrate.In the past couple of years ATRAP suffered serious setbacks due to vacuum leaks in the apparatus whichwere solved in late 2016. ATRAP is again ready and back in business. The goal of this presentation isto give an overview the ATRAP experiment.
23
14
ASACUSA CUSP antihydrogen beam experiment
N. Kuroda1, C. Amsler2, H. Breuker3, P. Dupre3, M. Fleck2,H. Higaki4, Y. Kanai3, B. Kolbinger2, M. Leali5,6, V. Mackel3,C. Malbrunot7, V. Mascagna5,6, O. Massiczek2, Y. Matsuda1,
Y. Nagata8, B. Radics9, M.C. Simon2, M. Tajima1,3, S. Ulmer3,L. Venturelli5,6, E. Widmann2, Y. Yamazaki3, and J. Zmeskal2
1. University of Tokyo, 153-8902 Tokyo, Japan2. Stefan-Meyer-Institut fur Subatomare Phyisk, 1090 Wien, Austria
3. RIKEN, 351-0198 Saitama, Japan4. Hiroshima University, 739-8530 Hiroshima, Japan
5. Universita di Brescia, 21533 Brescia, Italy6. Istituto Nazionale di Fisica Nucleare, 27100 Pavia, Italy
7. CERN, 1211, Genve, Switzerland8. Tokyo University of Science, 162-8601 Tokyo, Japan
9. Eidgenossische Technische Hochschule Zurish, 8092 Zurich, Switzerland
The aim of the ASACUSA CUSP experiment is a stringent test of CPT symmetry through a precisionspectroscopy of ground-state hyperfine structure of antihydrogen [1, 2]. We have developed an anti-atomicbeam method based on the classical Rabi-type beam spectroscopy, and have already demonstrated thesynthesis of antihydrogen atoms [3] and the production of an antihydrogen beam [4] with prototypeapparatuses.We have been developing a novel double-cusp trap to obtain enough number of spin-polarized ground-stateantihydrogen atoms for the hyperfine spectroscopy. The double-cusp trap functions with a combinationof an electrostatic potential well provided by multiple ring electrodes and a double cusp magnetic fieldwhich is an aligned configuration of two magnetic cusps by two pairs of anti-Helmholtz coils. The fieldconfiguration of the double-cusp trap sorts out spin states of antihydrogen atoms and thus provides aspin-polarized beam [5].In this talk, an overview of the ASACUSA CUSP experiment will be presented. We will also discussattempted various mixing schemes with the double-cusp trap to increase the production rate of antihy-drogen atoms and the first measurement of quantum states of formed antihydrogen atoms [6, 7].
References
[1] E. Widmann et al. The Hydrogen Atom: Precision Physics of Simple Atomic Systems, p.528–542,Springer, (2001).[2] A. Mohri and Y. Yamazaki, Europhys. Lett. 63 207–213 (2003).[3] Y. Enomoto et al. Phys. Rev. Lett. 105 243401 (2010).[4] N. Kuroda et al. Nat. Commun. 5 3089 (2014).[5] Y. Nagata et al. JPS Conf. Proc. 18 011007 (2017).[6] M. Tajima et al. JPS Conf. Proc. 18 011008 (2017).[7] C. Malbrunot et al. Philos. Trans. Royal. Soc. A 376 20170273 (2018).
24
15
1S-2S Spectroscopy of Antihydrogen in the ALPHA
Experiment
Chris Ø. Rasmussen1
1. CERN
Precision measurements of magnetically trapped antihydrogen provides a unique and powerful way to testmatter-antimatter symmetries. A cornerstone of the standard model, CPT symmetry demands that thespectrum of antihydrogen be identical to that of its ordinary matter counterpart. Of particular interestis the 1S-2S transition which has been measured in hydrogen[1] with the remarkable relative precisionof a few parts in 1015, and promises a particularly elegant and high precision test of CPT symmetry bycomparison to antihydrogen.Recently, the ALPHA collaboration made the first observation[2] of the 1S-2S transition in antihydrogen,which put a one-sided bound on the transition frequency with a relative precision of about 2 × 10−10
while being consistent with the hydrogen frequency.In this talk, I will present the latest advances in 1S-2S spectroscopy in antihydrogen along with themethods developed by the ALPHA collaboration to perform spectroscopy on small samples of trappedantihydrogen atoms. Finally, I will present some of the future improvements needed to take this milestonemeasurement to the same precision as its hydrogen counterpart.
Figure 1: The central components of the ALPHA apparatus. All components shown to scaleexcept for the annihilation detector, which extends to a larger radius than shown.
References
[1] Parthey, C.G. et al, Phys. rev. lett. 107, 203001 (2011).[2] Ahmadi, M. et al, Nature 541, 506-510 (2017).
25
16
The AEGIS Antimatter Gravity Experiment
Daniel Krasnicky1, on behalf of the AEgIS collaboration2
1. INFN Genova, Via Dodecaneso 33, 16146 – Genoa, Italy2. http://aegis.web.cern.ch/aegis/
The AEgIS experiment aims to measure the local gravitational acceleration of antimatter to make adirect test of the weak equivalence principle of General Relativity on a matter-antimatter system. Thetechnique pursued is to create a pulsed cold antihydrogen beam through the charge-exchange reactionbetween antiprotons and positronium to then measure such beam’s deflection in the gravitational field ofthe Earth with the use of a moire deflectometer. In this talk a general overview of the experiment and thegravity measurement technique will be given. Also, recent developments in the antimatter manipulationtechniques in AEgIS will be presented with the main emphasis given to a new positron injection schemeand to antiproton and electron ballistic transfer techniques used within the main AEgIS trap system.
26
17
Status of the GBAR experiment at CERN
Bruno Mansoulie1, on behalf of the GBAR collaboration1. CEA-IRFU Saclay, 91191 Gif-sur-Yvette CEDEX France
The GBAR experiment aims at measuring the free-fall of antihydrogen atoms. It is located at CERN inthe AD area and will be connected to the new ELENA low-energy antiproton ring. Installation of thefirst components has started during the second half of 2017. The status and plans of the experiment willbe given in this talk.
27
18
Measuring antimatter gravitation with trapped
antihydrogen: The ALPHA-g experiment
William BertscheUniversity of Manchester, Manchester, UK
The ALPHA experiment is expanding its experimental programm to include a dedicated instrument formeasuring antimatter gravitation. We are building on our success in routine antihydrogen confinementto expand a proof-of-principle method first demonstrated in the original ALPHA apparatus to a precisemeasurement of antimatter gravitational acceleration. The ALPHA-g experiment will measure annihila-tion distributions from trapped populations of antihydrogen atoms as escape by controlled-release fromour magnetic minimum trap. By measuring the antihydrogen distribution, as well as trap fields, thegravitational potential for antihydrogen atoms can be inferred. The ultimate goal for the first generationof this apparatus is to achieve a measurement of antihydrogens gravitational acceleration at the 1% level.
[1] The ALPHA Collaboration & A. E. Charman. Description and first application of a new techniqueto measure the gravitational mass of antihydrogen. Nature Communications 4, 1785 (2013)
28
19
New in-beam measurement of the hydrogen
hyperfine splitting and prospects
C. Malbrunot1,2
on behalf of the ASACUSA-CUSP collaboration1. CERN, Geneve 23, CH-1211, Switzerland
2. Stefan-Meyer-Institut fur subatomare Physik, der Osterreichischen Akademie der Wissenschaften,Boltzmanngasse 3, A-1090, Austria
The goal of the ASACUSA-CUSP collaboration at the Antiproton Decelerator of CERN is to measurethe ground-state hyperfine splitting of antihydrogen using an atomic spectroscopy beamline down torelative precisions of 10−6 − 10−7. A milestone was achieved in 2012 through the successful detectionof 80 antihydrogen atoms 2.7 meters away from their production region. This was the first observa-tion of “cold” antihydrogen in a magnetic field free region [1]. However the spectroscopy measurement iscurrently limited by the low flux of ground state antihydrogen atoms at the exit of the formation region [2].
In parallel to the work on the antihydrogen production, the spectroscopy beamline intended to be used forantihydrogen spectroscopy was tested with a source of hydrogen. This led to a measurement at a relativeprecision of 10−9 which constitues the most precise measurement of the hydrogen hyperfine splitting in abeam [3]. This measurement also enabled to forecast the necessary conditions to achieve a measurementat the ppm level with antihydrogen.
The hyperfine splitting in hydrogen reported in [3] was determined using extrapolation of one of theground state hyperfine transitions measured at different external magnetic fields. The apparatus hassince been modified to allow simultaneous measurements of two transitions which in principle allows adetermination of the zero-field hyperfine splitting will less atoms; something of great interest for theantihydrogen experiment.
I will review the experimental techniques used and the latest results obtained as well as the prospects forfurther measurements on hydrogen using the same apparatus for tests of Lorentz symmetry.
References
[1] N. Kuroda et al., Nature Communications 5, 3089 (2014).[2] C. Malbrunot et al., Philosophical Transactions A, issue on “Antiproton physics in the ELENAera” doi:10.1098/rsta/376/2116 (2018)[3] Diermaier et al., Nature Communications 8,15749 (2017)
29
Talks
Wednesday 14th
30
20
Nuclear stopping power of antiprotons
K. Nordlund1, D. Sundholm2, D. M. Zambrano3,4, F.Djurabekova1 and P. Pyykko2
1. Helsinki Institute of Physics and Department of Physics, P.B. 43, University of Helsinki, Finland2. Department of Chemistry, P.B. 55, University of Helsinki, Finland
3. Northwestern University, Department of Physics, Evanston, IL, USA4. CERN, Geneva 23, 1211, Switzerland
The slowing down of energetic ions in solids is determined by the nuclear and electronic stopping powers.Both of these have been studied extensively for ordinary matter ions. For antiprotons, however, there arenumerous studies of the electronic stopping power, but none of the nuclear one. Here, we use quantumchemical methods to calculate interparticle potentials between antiprotons and different atoms, andderive from these the nuclear stopping power of antiprotons in several solids. The results show that theantiproton nuclear stopping powers are much stronger than those of protons, and can also be strongerthan the electronic stopping power at the lowest energies (see Fig. 1) The interparticle potentials are alsoimplemented in a molecular dynamics ion range calculation code, which allows to simulate antiprotontransmission through degrader foil materials. Foil transmission simulations carried out at experimentallyrelevant conditions show that the choice of antiproton-atom interaction model has a large effect on thepredicted yield of antiprotons slowed down to low (a few keV) energies [1].
10-3
10-2
10-1
S(k
eV
/nm
)
10-2
10-1
1 10 102
E (keV)
Sn
Se
Antiprotons
10-3
10-2
10-1
S(k
eV
/nm
)
10-2
10-1
1 10 102
103
E (keV)
Sn
Se
Protons
Figure 1: Nuclear Sn and electronic Se stopping powers of antiprotons in Si (left) and protonsin Si (right)
We use the simulation approach developed to simulate systematically the slowing down of 100 keVantiprotons, that will be produced in the ELENA storage ring under construction at CERN, in energydegrading foils. The results predict that the optimal foil thickness for slowing down the antiprotons from100 keV to below 5 keV is 910 nm in Al foils [2] and 1500 nm in Si foils [1]. Also the lateral spreading ofthe transmitted antiprotons is reported and the uncertainties discussed.
References
[1] K. Nordlund, D. Sundholm, D. Martinez Zambrano, and F. Djurabekova and P. Pyykko, Phys. Rev.A 96, 042717 (2017)[2] K. Nordlund, Results in physics (2018), accepted for publication.
31
21
Differential cross sections in collisions of low-energy
antiprotons with ions and atoms
A. I. Bondarev1,2, A. V. Maiorova1,2, V. M. Shabaev1,G. Plunien3, and Th. Stohlker4,5,6
1. Department of Physics, St. Petersburg State University, 199034 St. Petersburg, Russia2. Center for Advanced Studies, Peter the Great St. Petersburg Polytechnic University, 195251
St. Petersburg, Russia3. Institut fur Theoretische Physik, Technische Universitat Dresden, D-01062 Dresden, Germany
4. GSI Helmholtzzentrum fur Schwerionenforschung GmbH, D-64291 Darmstadt, Germany5. Helmholtz-Institute Jena, D-07743 Jena, Germany
6. Institut fur Optik und Quantenelektronik, Friedrich-Schiller-Universitat, D-07743 Jena, Germany
The facility for antiproton and ion research being constructed in Darmstadt as well as the renovated fa-cility at CERN will provide high-quality antiproton beams. This will allow to perform various collisionalexperiments with low-energy antiprotons. In addition, latest progress in experimental technique of therecoil-ion and electron momentum spectroscopy enables one to carry out kinematically complete exper-iments and measure fully differential cross sections (FDCS) for ionization in ion-atom collisions. Suchcross sections contain the most complete information on ionization dynamics and provide very stringenttest of theoretical models.An experimental investigation of the FDCS in this collision is not possible at the moment. Neverthe-less, the ionization cross sections have already been extensively studied theoretically by various non-perturbative methods [1, 2, 3, 4]. However, several results, obtained by these methods, considerablydiffer. Within our independent calculation [5], we can give preference to the results of certain approachesand resolve some discrepancies.Besides, the Coulomb glory occurring in elastic scattering of low-energy antiprotons off ions will bereviewed. This phenomenon consists of a prominent maximum of the differential cross section in thebackward direction at a certain energy of the incident antiproton, provided the interaction with a targetis represented by the Coulomb attraction of the nucleus screened by atomic electrons. The effect was firstpredicted by Demkov and co-workers [6, 7] and further elaborated in Refs. [8, 9, 10]. Our investigations canassist in experiment designing for the first observation of the Coulomb glory in scattering of antiprotons.
References
[1] M. McGovern et al., Phys. Rev. A 79, 042707 (2009).[2] I. B. Abdurakhmanov et al., J. Phys. B 44, 165203 (2011).[3] M. F. Ciappina et al., Phys. Rev. A 88, 042714 (2013).[4] I. B. Abdurakhmanov, A. S. Kadyrov and I. Bray, Phys. Rev. A 94, 022703 (2016).[5] A. I. Bondarev et al., Phys. Rev. A 95, 052709 (2017).[6] Yu. N. Demkov, V. N. Ostrovsky and D. A. Telnov, Sov. Phys. JETP 59, 257 (1984).[7] Yu. N. Demkov and V. N. Ostrovsky, J. Phys. B 34, L595 (2001).[8] A. V. Maiorova et al., Phys. Rev. A 76, 032709 (2007).[9] A. V. Maiorova et al., J. Phys. B 41, 245203 (2008).[10] A. V. Maiorova et al., J. Phys. B 43, 205006 (2010).
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22
Laser cooling of anions for ultracold antihydrogen
Alban Kellerbauer, Giovanni Cerchiari and Pauline YzombardMax Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany
For experiments studying antihydrogen – either by spectroscopy or by matter wave interferometry – itis crucial to produce ultracold anti-atoms in order to reach the highest possible precision. One of asmall number of possible avenues towards this goal is the pre-cooling of antiprotons using laser-cooledanions [1]. Currently available cooling techniques for negatively charged particles allow cooling only tothe temperature of the surrounding environment, typically a few kelvin. In this scheme, a fast electronictransition in an atomic anion will be used to laser-cool it to microkelvin temperatures. Ensembles ofany other negative ions (including antiprotons) can then be indirectly cooled by Coulomb collisions(sympathetic cooling). Until now, there are only three known atomic anions with bound–bound electric-dipole transitions. We have investigated such transitions in two of these candidates, Os− [2] and La−
[3,4], by high-resolution laser spectroscopy in order to test their suitability for laser cooling. The principleof the method, its potential applications, as well as recent experimental results will be presented.
References
[1] A. Kellerbauer and J. Walz, “A novel cooling scheme for antiprotons,” New J. Phys. 8, 45 (2006).[2] U. Warring et al., “High-resolution laser spectroscopy on the negative osmium ion,” Phys. Rev. Lett.
102, 043001 (2009).[3] E. Jordan et al., “High-resolution spectroscopy on the laser-cooling candidate La−,” Phys. Rev. Lett.
115, 113001 (2015).[4] G. Cerchiari et al., “Ultracold anions for high-precision antihydrogen experiments,” (2018), submitted.
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23
Cooling of mixed ion crystals for GBAR
Sebastian Wolf1 and Ferdinand Schmidt-Kaler1
1. QUANTUM, Institut fur Physik, Johannes Gutenberg-Universitat Mainz, Germany
The GBAR collaboration aims for a direct measurement of the gravitational interaction between matterand anti-matter via the free fall of single anti-hydrogen atoms in the earth gravitational field [1]. Theanti-hydrogen will be produced at the ELENA/AD facility at CERN. To minimize the initial velocitydistribution for the free-fall experiment the anti-hydrogen will be created in a positivly charged state,consisting of one anti-proton and two positrons. This anti-ion will be trapped in a Paul trap and sym-pathetically cooled by co-trapped 9Be+ ions. The capturing will be done in a two-stage process. In afirst macroscopic capture trap with order 106 beryllium ions the anti-hydrogen ions will be cooled below100 mK. They then are transported to a precision trap and cooled below 100µK using a single Be+ ionusing the elaborated laser cooling schemes developed in the ion trapping community. The mixed ioncrystal will be cooled into the motional ground-state of the harmonic trap potential. To further optimizethe velocity uncertanity the vertical confinement will be ramped down adiabatically keeping the ions inthe ground-state [2]. A major challenge is the mass ratio of beryllium and anti-hydrogen of 9/1 causinga small coupling between the two species [3].We report on the status of the Paul trap experiment for sympathetic cooling and adiabatic expansion.Mixed crystals of 40Ca+ and 9Be+ ions are captured in a micro-strucured linear Paul trap. An improvedtrap construction procedure provides low heating rates, even at low trap frequencies below 200 kHz,a critical prerequisite for both, ground-state cooling and the adiabatic release of ions. We show firstexperimental results of mixed-crystal side-band spectra and sub-Doppler cooling. Optimized voltageramps for decreasing the trap frequency and velocity spread guarantee a minimized heating of the ions.We discuss a new, accelerator hall approved, efficient resonant laser ionization setup for beryllium [4]and the laser system for Doppler cooling of beryllium. A new design for the trap used to first capturethe anti-ions from the decelerator beam is discussed. The capture trap has to be suitable for trappingof a large number of beryllium ions in a relatively large trapping volume and needs segmentation toseperate beryllium from anti-hydrogen after cooling. The lithographically contructed trap on quartzwafers [5] solves the difficulty in seperating the incoming ion beam from the axial Doppler cooling laserby introducing three trapping zones divided by a small angle. For imaging of the ion fluorescence we usea conducting, transparent ITO (indium tin oxide) layer.
References
[1] P. Perez and Y. Sacquin, Class. Quantum Grav. 29, 184008 (2012).[2] D Guery-Odelin and J. G. Muga, Phys. Rev. A 90, 063425 (2014).[3] J. Wubbena et al., Phys. Rev. A 85, 043412 (2012).[4] S. Wolf et al., Appl. Phys. B 124:30 (2018).[5] support by M. Keil and R. Folman, Ben-Gurion University, Israel.
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24
Lyman-α source for laser cooling antihydrogen
Gerald Gabrielse1, Bartosz Glowacz3, Dieter Grzonka4, EricHessels6, Nathan Jones1, Ghanshyambhai Khatri1, Siu-Au Lee2,
Tharon Morrison1, Edouard Nottet5, Cory Rasor2, CodyStorry6, Eric Tardiff1, Dylan Yost2, Daniel Martinez Zambrano5,
Marcin Zielinski3
1. Department of Physics, Harvard University, Cambridge, MA 02138, USA2. Department of Physics, Colorado State University, Fort Collins, CO 80523, USA
3. Faculty of Physics, Astronomy, and Applied Computer Science, Jagiellonian University, 30-059Krakow, Poland
4. Forschungzentrum Juelich GmbH, D-52425, Juelich, Germany5. Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
6. Department of Physics and Astronomy, York University, Toronto, Ontario M3J 1P3, Canada
We present a Lyman-α laser developed for cooling trapped antihydrogen. The system is based on a pulsedTi:sapphire laser operating at 729 nm that is frequency doubled using an LBO crystal and then frequencytripled in a Kr/Ar gas cell. After frequency conversion, this system produces up to 5.7 µW of averagepower at the Lyman-α wavelength. This laser is currently operating at the CERN ATRAP experiment.
35
25
Antihydrogen formation via charge exchange
between positronium and antiproton
Nicola Zurlo1,2, on behalf of the AEgIS collaboration3
1. DICATAM, University of Brescia, via Branze 43, 25123 Brescia, Italy2. INFN Sezione di Pavia, via Bassi 6, 27100 Pavia, Italy
3. http://aegis.web.cern.ch/aegis/
Since the first synthesis of cold antihydrogen [1], most experiments in the same field have exploited(and substantially improved) the same technique, based on the mixing of positrons and antiprotonsclouds interacting via three body recombination, with only one relevant exception [2]; in this paper, thefeasibility of a different way to antihydrogen production was demonstrated, via antiproton-positroniumcharge exchange mediated by cesium atoms, along the lines of a method first proposed in a pioneeringwork published in 1986 [3].The AEgIS experiment aims at producing antihydrogen (and eventually measuring the effects of theEarth gravitational field on it) with a similar method, based on the charge exchange reaction betweenantiproton (p) and positronium (Ps):
p+ Ps∗ → H∗ + e−
where positronium (Ps) is produced by positrons implantation on a mesoporous silica target and subse-quently excited to a Rydberg state via double step laser excitation [4].This process can be in principle much more efficient than the traditional mixing process, because of thelarge cross section for Rydberg charge exchange, and has the advantage that the final H quantum statescan be predicted as a function of the initial Ps∗ quantum states, and their distribution is relatively narrow,so that they can be accelerated by electric field gradients. Moreover, antiprotons can be preemptivelycooled in order to reduce their transverse velocity and make a collimated beam of antihydrogen.In this contribution, we will focus on Monte Carlo simulations designed for the assessment of the Ps laserexcitation in the antiproton Penning trap region, and then developed to give a realistic estimation of theantihydrogen production rate.
References
[1] M. Amoretti et al., Nature 419 (2002)[2] C.H. Storry et al., Phys. Rev. Lett. 93, 263401 (2004).[3] B.I. Deutch et al., Proceedings of The First Workshop on Antimatter Physics at Low Energy, 371(1986).[4] S. Aghion et al. Phys. Rev. A 94, 012507 (2016).
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26
A new approach for measuring antiproton
annihilation at rest with Timepix3
A. Gligorova 1, on behalf of the AEgIS and ASACUSAcollaborations
1. Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3,1090 Vienna, Austria
Ultra precise tests of CPT (charge, parity, time) symmetry, in view of the baryon asymmetry in theUniverse is the main motivation for the experiments at the Antiproton Decelerator (AD) at CERN.Most of them focus on studying antihydrogen - the only stable, neutral antimatter system availablefor laboratory study. Crucial to the success of these experiments is the efficient detection and correcttagging of antiprotons and antihydrogen. Mostly it is achieved with tracking detectors, through thereconstruction and extrapolation of the trajectories of charged pions produced in the annihilation process[1,2,3,4]. These detectors determine the time and position of antiproton annihilations and usually consistof layers of silicon strip modules [1,2] or scintillating bars and fibres [3,5].We present here a different detection method, using a pixel detector, where the antiprotons annihilateinside the detector volume or in a thin foil in front of it. This approach gives high resolution on theannihilation position (tens of µm), making it dominant for experiments with such requirement [6]. Whenintegrated with a conventional tracking detector, the method makes possible to detect and identify mostof the products in antiproton-nucleus annihilation (charged pions, protons, alphas and heavy fragments).A detailed study of their multiplicity and energy distributions is essential for tuning the physics modelsin the Monte Carlo simulations (e.g. GEANT4) in the low-energy region.This work incorporates studies from two AD experiments, employing the Timepix3, an ASIC hybriddetector developed by CERN’s Medipix3 collaboration, characterised with high spatial resolution andnanosecond precision on the Time-of-Arrival and Time-over-Threshold [7]. Direct detection of antipro-tons was performed on a dedicated beam line within AEgIS [8], providing quantitative results on thetagging efficiency and the position resolution of the annihilation point, which will be discussed [9]. Themeasurement of the multiplicity and energy distributions of the prongs in antiproton annihilations indifferent materials was set up in ASACUSA, where the information from a quad array of Timepix3 andthe existing hodoscope was combined [3]. The advantages of having two detectors and a first glimpse onthe results will be presented.
References
[1] M. Amoretti et al., Nucl.Instrum.Meth. A 518 679-711 (2004)[2] G.B. Andresen at al., Nucl.Instrum.Meth. A 684, 73-81 (2012)[3] C. Sauerzopf et al., Nucl.Instrum.Meth. A 845, 579-582 (2016)[4] B. Radics et al., Rev. Sci. Instrum. 86, 083304 (2015)[5] J. Storey et al., Nucl.Instrum.Meth. A 732, 437-441 (2013)[6] M. Doser et al., Class. Quantum Grav. 29 184009 (2012)[7] T. Poikela et al., Journal of Instrumentation 9 C05013 (2014)[8] N. Pacifico et al., Nucl.Instrum.Meth. A 831 12-17 (2016)[9] S. Aghion et al., Antiproton tagging and vertex fitting using a silicon pixel detector with a Timepix3readout, in preparation
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27
The PANDA experiment at FAIR
Egle Tomasi-Gustafsson[on behalf of the PANDA Collaboration]
IRFU, CEA, Universite Paris-Saclay, 91191 Gif-sur-Yvette Cedex, France
The PANDA experiment, is a core project of the future Facility for Antiproton and Ion Research (FAIR)at GSI in Darmstadt [1]. It will investigate antiproton proton annihilations on nucleons and nuclei withthe aim to explore fundamental questions in the nonperturbative regime of QCD as the origine of thehadron mass. The multi-purpose detector is currently under construction. The intense and high qualityanti-proton beam will span the momentum range between 1.5 and 15 GeV/c. The detection of hadrons,leptons, and photons in the final states will be possible with very high precision. A rich physics programas resonances in the charmonium and open charm region, electromagnetic form factors, hyper nuclearphysics will be investigated. The worldwide collaboration gathers today more than 450 physicists from60 institutions in 19 countries. The talk will give an overview of the PANDA experiment and of the mostimportant aspects of the physics program. It will focus on the topics that will be investigated as soon asthe facility is operational.
References
[1] K. Peters, L. Schmitt, T. Stockmanns and J. Messchendorp, Nucl. Phys. News 27, no. 3, 24 (2017)and references therein.
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28
GAPS, low-energy antimatter for indirect
dark-matter search
Vannuccini E.1, on behalf of the GAPS Collaboration1. INFN, Sezione di Firenze (Italy)
The General Antiparticle Spectrometer (GAPS) is designed to carry out a sensitive dark matter search bymeasuring low-energy cosmic-ray antiparticles. Below a few GeVs the flux of antiparticles produced bycosmic-ray collisions with the interstellar medium is expected to be very low and several well-motivatedbeyond-standard models predict a sizable contribution to the antideuteron flux. GAPS is planned tofly on a long-duration balloon over Antarctica in the austral summer of 2020. The primary detector isa ∼1m3 central volume containing planes of Si(Li) detectors. This volume is surrounded by a time-of-flight system to both trigger the Si(Li) detector and better reconstruct particle tracks. The detectionprinciple of the experiment relies on the identification of the antiparticle annihilation pattern. Low energyantiparticles slow down in the apparatus and they are captured in the medium to form exotic excitedatoms, which de-excite by emitting characteristic X-rays. Afterwards they undergo nuclear annihilation,resulting in a star of pions and protons. The simultaneous measurement of the stopping depth and thedE/dx loss of the primary antiparticle, of the X-ray energies and of the star particle-multiplicity providesvery high rejection power, that is critical in rare-event search. GAPS will be able to perform a precisemeasurement of the cosmic antiproton flux below 250 MeV, as well as a sensitive search for antideuterons.This presentation will address the physical motivation of the experiment, discuss the current status andgive an update on the payload design.
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29
A Detector for Measuring the Ground State
Hyperfine Splitting of Antihydrogen
B. Kolbinger1, C. Amsler1, H. Breuker2, M. Diermaier1,P. Dupre2, M. Fleck1, A. Gligorova1, H. Higaki3, Y. Kanai4,
T. Kobayashi5, N. Kuroda5, M. Leali6, V. Mackel1,C. Malbrunot7, V. Mascagna6, O. Massiczek1, Y. Matsuda5,
D.J. Murtagh1, Y. Nagata8, C. Sauerzopf1, M.C. Simon1,M.Tajima4, S. Ulmer2, L. Venturelli6, E. Widmann1,
Y. Yamazaki2, J. Zmeskal1
1. Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences,Boltzmanngasse 3, 1090 Vienna, Austria
2. Ulmer Fundamental Symmetry Laboratory, RIKEN, Saitama 351-0198, Japan3. Graduate School of Advanced Science of Matter, Hiroshima University, Kagamiyama,
Higashi-Hiroshima, 739-8530 Hiroshima, Japan4. Nishina Center for Accelerator-Based Science, RIKEN Saitama 351-0198, Japan
5. Institute of Physics, University of Tokyo, 153-8902, Japan6. Dipartimento di Ingegneria dell’Informazione, Universita degli Studi di Brescia, I-25133 Brescia,
Italy and Istituto Nazionale di Fisica Nucleare, Sez. di Pavia, I-27100 Pavia, Italy7. CERN 1211, Geneva 23, Switzerland
8. Department of Physics, Tokyo University of Science, Shinjuku, Tokyo 162-8601, Japan
The combined symmetry of charge conjugation, parity and time reversal (CPT) is a pillar of the StandardModel and no violation has been found so far. As a consequence matter and antimatter are predictedto have equal or sign-opposite properties. Nonetheless the observed matter-antimatter asymmetry in theuniverse cannot be explained quantitatively.The ASACUSA Collaboration at CERNs Antiproton Decelerator aims for a precise CPT test by measuringthe ground state hyperfine splitting of antihydrogen. Antiprotons and positrons form antihydrogen [1]in a double CUSP trap, the antiatoms escape the trap as a beam and enter a Rabi-like spectrometerapparatus [2]. A detector records the annihilation signal at the end of the beamline. Its purpose isto count the arriving antihydrogen atoms and also distinguish signal from background events (mainlycosmics).The detector consists of a central scintillator disk with position sensitive readout and a surroundingtwo layered tracking detector [3] made up of plastic scintillators with silicon photo multiplier readout.Its time resolution allows to differentiate between particles coming from inside and those traversing thedetector from outside. In order to enable 3D tracking and precise vertex reconstruction, an upgrade hasbeen implemented using scintillating fibres. A machine learning analysis has been developed in orderto discriminate signal from background. The algorithm has been trained using events acquired duringantiproton extractions to the detector and background events recorded in beam-off periods. Recentmeasurements [4] will be discussed in the light of this data-driven analysis.
References
[1] N. Kuroda et al., Nature Communications 5, 3089 (2014).[2] C. Malbrunot et al., Hyperfine Interactions 228, 6166 (2014)[3] C. Sauerzopf et al., NIMA A845, 579-582 (2016)[4] C. Malbrunot et al., RSA, DOI: 10.1098/rsta/376/2116 (2017)
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Testing CPT with the Anti-hydrogen Molecular Ion
Edmund G. Myers, David J. Fink and Jordan A. SmithFlorida State University, Physics Department, Tallahassee, FL 32306-4350, USA
High precision radio-frequency, microwave and infra-red spectroscopic measurements of the anti-hydrogenmolecular ion H−2 (ppe+), compared with its normal matter counterpart H+
2 , can provide direct testsof the CPT theorem. The fractional precision that can be achieved with such measurements can exceedthat from comparing anti-protons with protons or anti-hydrogen with hydrogen. Schemes are outlinedfor measurements on a single H−2 ion in a Penning trap, that use non-destructive state identification bymeasuring the cyclotron frequency and positron spin-flip frequency (using the continuous Stern-Gerlachtechnique), and also methods for creating an H−2 ion and initializing its quantum state.
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31
Toward an improved comparison of the
proton-to-antiproton charge-to-mass ratio
Takashi Higuchi1,2, James Harrington1,3,Matthias Borchert1,4, Jonathan Morgner1,4, Stefan Sellner1,Christian Smorra1, Andreas Mooser1, Georg Schneider1,5,
Natalie Schn5, Markus Wiesinger1,3, Klaus Blaum3,Yasuyuki Matsuda2, Christian Ospelkaus4,6, Wolfgang Quint7,
Jochen Walz5,8, Yasunori Yamazaki1 and Stefan Ulmer1
1. Ulmer Fundamental Symmetries Laboratory RIKEN, Wako, Japan2. Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan
3. Max-Planck-Institut fr Kernphysik, Heidelberg, Germany4. Institut fr Quantenoptik, Leibniz Universitt Hannover, Hannover, Germany5. Institut fr Physik, Johannes Gutenberg-Universitt Mainz, Mainz, Germany
6. Physikalisch-Technische Bundesanstalt, Braunschweig, Germany7. GSI-Helmholtzzentrum fr Schwerionenforschung, Darmstadt, Germany
8. Helmholtz-Institut Mainz, Mainz, Germany
The BASE collaboration [1] conducts high-precision comparisons of the fundamental properties of theproton and the antiproton as stringent tests of CPT symmetry, such as a high-precision comparison oftheir charge-to-mass ratios. We performed such a measurement in 2014 [2], and currently aim to furtherimprove the precision.The principle of the measurement is to compare the cyclotron frequencies ωc = qB/m of a single an-tiproton and a negative hydrogen ion H− in the same magnetic field B. The mass of the proton can becalculated from that of the H− with sub p.p.t. fractional accuracy, which enables us to compare (q/m)pand (q/m)p with high precision.In 2017, we commissioned an apparatus dedicated to such a measurement. The cyclotron frequencystability in the apparatus has been improved by a new magnetic shielding system and optimization ofvarious environmental conditions to a point where we finally reached to a stability better than in 2014by a factor > 2.In this presentation, different aspects of optimization procedures performed during CERN’s 2017 AD runwill be summarized.
References
[1] C. Smorra, et al., Eur. Phys. J. S.T. 224, 3055 (2015).
[2] S. Ulmer, et al., Nature 524, 196 (2015).
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Electric dipole moment of light nuclei
Nodoka Yamanaka1,2
1. IPNO, Universite Paris-Sud, CNRS/IN2P3, F-91406, Orsay, France2. iTHES Research Group, RIKEN, Wako, Saitama 351-0198, Japan
The measurement of the electric dipole moment (EDM) is an excellent test of the standard model ofparticle physics, and the detection of a finite value is signal of a new source of CP violation beyond it. Inthis talk, we review the EDM of light nuclei in the theoretical point-of-view. We discuss the enhancementand the suppression of the EDM of light nuclei which strongly depend on the nuclear structure [1].
References
[1] Nodoka Yamanaka, Int. J. Mod. Phys. E 26, 1730002 (2017).
43
Talks
Thursday 15th
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33
Low-energy antiproton scattering
A. S. Kadyrov1, I. B. Abdurakhmanov1, K. Bartschat2, I. Bray1,M. Charlton3, I. I. Fabrikant4, D. V. Fursa1 and C. M. Rawlins1
1Department of Physics and Astronomy, Curtin University, GPO Box U1987, Perth, WA6845, Australia2Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311, USA
3Department of Physics, College of Science, Swansea University, SA2 8PP, UK4Department of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588-0111, USA
The two-centre convergent close-coupling (CCC) approach is a general-purpose formalism applicable toa wide range of atomic collision processes. It was originally developed for positron scattering on atomichydrogen including positronium (Ps) formation, see [1] and references therein. The CCC approachcombines the expansion of the total wave function over the atomic states with that over the Ps states. Sucha double expansion allows for explicit Ps formation, and allows for the distinction within the ionisationprocesses between Ps-formation and breakup channels. The approach is based on discretisation of thecontinuum and provides the complete solution to the three-body problem.The quantum-mechanical CCC method was applied to study antihydrogen formation in the reactionPs(ni, li) + p → H(n′, l′) + e− at low energies [2]. We found increases of several orders of magnitudein H-formation cross sections σH when ni was raised from 1 to 2 and 3, with the cross sections for theexcited states displaying a characteristic 1/E dependence at low Ps kinetic energies E. Recently we haveextended the previous studies by considering Ps principal quantum numbers up to ni = 5 [3]. We haveestablished that the dramatic increase in σH, when ni is increased from 2 to 3 and from 1 to 2, wasabsent for the higher values of ni. In the Ps kinetic energy region where the data for all ni behave as1/E, there is only a factor of around 3 between the σH for ni = 5 when compared to ni = 3. This is tobe contrasted with the approximately factor of 30 increase between ni = 2 and 3, and a several orders ofmagnitude enhancement in the formation of H via p scattering with Ps in an ni = 2 excited state overthe ground state [2]. It has been concluded that quantum effects dramatically suppress the increase ofσH, in sharp contrast to expectations from Bohr-like and classical theories. If the trend in σH persistsat high ni, then the implications for current experimental efforts, which aim to exploit efficient chargetransfer from excited-state Ps to produce H, could be severe.The CCC approach has also been generalised to heavy particle collisions and applied to study low-energyp scattering on atomic and molecular targets, see [4] and references therein. The continuous spectrum ofthe target is discretised using stationary wave packets constructed from the Coulomb wave function. Theapproach has been applied to calculate cross sections for p collisions with various targets and excellentagreement with experiment has been observed where data are available [5]. A comprehensive set ofbenchmark results from integrated to fully differential cross sections for p -impact ionisation in theenergy range from 1 keV to 1 MeV has been obtained.
References
[1] A. S. Kadyrov and I. Bray, J. Phys. B: At. Mol. Opt. Phys. 49, 222002 (2016).[2] A. S. Kadyrov et al., Phys. Rev. Lett. 114, 183201 (2015).[3] A. S. Kadyrov et al., Nature Commun. 8, 1544 (2017).[4] I. B. Abdurakhmanov et al., Phys. Rev. A 96 022702 (2017).[5] I. B. Abdurakhmanov et al., Phys. Rev. Lett. 111, 173201 (2013).
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Ab-initio calculations of reactions involving the
3-body system (p, e+, e−) between the e− + H(n = 2) and
e− + H(n = 3) thresholds
Marianne Dufour1, Mateo Valdes1, Rimantas Lazauskas1 andPaul-Antoine Hervieux2
1. Universite de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France2. Universite de Strasbourg, CNRS, IPCMS UMR 7504, F-67000 Strasbourg, France
Recently, we have developed a new method to solve Faddeev-Merkuriev equations using Lagrange-meshtechniques to describe collisions of the Coulombic three-body systems. This method has been applied tostudy (p, e+, e−) system in the energy range between the e− + H(n = 2) and e− + H(n = 3) thresholds[1]. Here, p stands for antiproton, e+ for positron, e− for electron, and H for antihydrogen. A specialemphasis is made on the first charge exchange reaction of GBAR, p+ Ps→ e− + H where Ps stands forthe positronium. But our results can also be of interest for future experiments on antimatter (AEGIS,...). One of the biggest challenges faced by GBAR is to find the best experimental and physical conditions(Ps state, antiproton energy etc...) to enhance the antihydrogen production. In this context, a specialfocus is made on the role played by Feshbach resonances and Gailitis-Damburg oscillations appearing inthe vicinity of the p+ Ps(n = 2) threshold.Our calculation show the existence of two Feshbach resonances, the first in the S-partial wave and thesecond in the P partial wave. In p+ Ps(n = 2)→ e− + H(n = 2) scattering cross sections we have beenable to highlight 4 Gailitis-Damburg oscillations, two in the S partial wave and, for the first time, two inthe D partial wave. We have also found, for the first time, a Gailitis-Damburg oscillation in the P -wavepartial cross section of antihydrogen excitation e− + H(n = 1) → e− + H(n = 2). In addition to thenew oscillations observed, our results are in very good agreement with previous works while giving moredetailed cross sections [2,3].
References
[1] M. Valdes, M. Dufour, R. Lazauskas, P.-A. Hervieux, Ab-initio calculations of 3-body system (p, e+, e−)between e− + H(n = 2) and e− + H(n = 3) thresholds, to be published in Phys. Rev. A.[2] C.-Y. Hu, D. Caballero, and Z. Hlousek, J. Phys. B: At. Mol. Opt. Phys. 34, 331 (2000).[3] A. S. Kadyrov, C. M. Rawlins, A. T. Stelbovics, I. Bray, and M. Charlton, Phys. Rev. Lett. 114,183201 (2015).
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Four-body treatment of the
antihydrogen-positronium system:
binding, structure, resonant states and collisions.
Piotr Froelich1, Takuma Yamashita2, Yasushi Kino2, SvanteJonsell3, Emiko Hiyama4, Konrad Piszczatowski1
1. Uppsala University, Department of Theoretical Chemistry - Angstrom Laboratory, Box 538, 751 21Uppsala, Sweden
2. Tohoku University, Department of Chemistry, Sendai 980-8578, Japan3. Stockholm University, Department of Physics, 106 91 Stockholm, Sweden
4. Strangeness Nuclear Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 Japan
We present the study of the binding, resonant and collisional properties of the H − Ps system. Thebinding energy, the life-times of the resonant states and the collisional cross sections are calculated anddiscussed.To describe the structure of the the H − Ps system we apply the variational approach based on theGaussian Expansion Method (GEM). The variational manifold explicitly contains components of vari-ous arrangement channels expressed in terms of corresponding Jacobi coordinates. The use of Jacobicoordinates allows an efficient and rigorous treatment of the scattering cross sections.The binding energy is calculated and discussed in terms of the contributions from various arrangementchannels. Channel analysis helps to converge the binding energy and throws light on the structure andcollisional properties of the system. The structure of the system is presented in terms of the correlationfunctions that portray the spatial distribution of the particles. This helps to understand the structureand dynamics of the system, in particular the change of the H+ upon binding of an electron, and thecoexistence of the atomic and molecular features of HPs.The resonant states and their life-times are calculated variationally using GEM in conjunction with theComplex Coordinate Method (CCM). The energies and widths of the resonances are analysed with respectto the channel composition of the resonant wave functions.Based on the variational description of the four-body system, we apply the coupled rearrangement chan-nels method to calculate the cross sections for H−Ps collisions. The outer part of the total wave functionis made to satisfy the appropriate scattering boundary conditions for the collisional fragments. This isfacilitated by the use of Jacobi coordinates in the description of the multi-channel structure of the wavefunction, that expressly contains various arrangement channels. The scattering matrix S and the crosssections are obtained from the coupled, non-local integro-differential equations that explicitly couple thecollisional channels of interest.
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Production of light (anti-)(hyper-)nuclei
in heavy-ion collisions
Silvia Masciocchi1
1. GSI Helmholtz Center for Heavy Ion Research, Planckstrasse 1, Darmstadt, and PhysikalischesInstitut, Heidelberg University, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
Collisions of heavy ions (such as Pb and Au) at ultra-relativistic energies provide excellent conditions tostudy the production of light nuclei and anti-nuclei, namely deuteron, triton, 3He, 4He and the lightesthyper-nucleus 3
ΛH, to date. The production rate and the kinematic properties of the light nuclei aremeasured, together with some of their fundamental properties such as the mass-to-charge ratio differencebetween matter and anti-matter and the lifetime of the hyper-triton.The abundance of the light nuclei created allows the investigation of their production mechanism. Thenuclei production is described via two main approaches, either by the statistical thermal model or withinthe coalescence scenario. Very interesting insights are also provided by measurements of nuclei productionin proton-proton and proton-ion collisions, as a function of the multiplicity of produced charged particles.Important information about the process of formation of nuclei can be acquired.Recent results from ALICE at the LHC, CERN, Geneva, and by STAR at RHIC, Brookhaven NationalLaboratory, Upton, will be presented. Both experiments profit from excellent detectors for particle iden-tification and high resolution track reconstruction. The figure below shows the specific energy loss ofpositively charged particles measured by the Time Projection Chamber of the ALICE experiment: thelight nuclei can be clearly distinguished from the very abundant light hadrons. Experimental measure-ments will be presented and their comparison with model calculations will be discussed. High statisticsmeasurements in the near future will make possible a significant progress in the field.
Figure 1: Specific energy loss of positively charged particles from Pb-Pb collisions at√sNN=2.76
TeV, as a function of the particle rigidity, measured by the ALICE Time Projection Chamber(the ALICE Collaboration).
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37
Guiding and manipulating Rydberg positronium
using inhomogeneous electric fields
A. M. Alonso, B. S. Cooper, A. Deller, L. Gurung, S. D. Hoganand D. B. Cassidy
Department of Physics and Astronomy, University College LondonGower Street, London, WC1E 6BT, UK
The short ground-state lifetime of Positronium (Ps) makes it challenging to perform precision-spectroscopystudies that require long interaction times. However, when excited to Rydberg states the annihilationrate of Ps becomes negligible [1], and the lifetime is dominated by fluorescence to low lying states. Inaddition, Rydberg Stark states with large Stark energy shifts have significant electric dipole momentswhich provide a mechanism by which forces can be applied to Ps atoms using inhomogeneous electricfields[2].In a recent series of experiments we selectively excited individual Stark-states of Ps [3], guided the atomsusing inhomogeneous electric fields in an atomic guide [4], and modified the guide to select a portion of thevelocity distribution of the atoms with kinetic energies of ∼45 meV [5]. Having a beam of slow RydbergPs atoms will lead to a number of applications including trapping Ps, measuring the Rydberg constant ina purely leptonic system [6], scattering and merged beams experiments, and potential antimatter gravitymeasurements.
Figure 1: (Left) Trajectory simulation for Ps in the ground state (a), n = 10 (b) and guidedn = 10 with inhomogeneous electric fields. (Center) Experimental setup and detector position.(Right) Measured and calculated fluorescence lifetimes of Rydberg states ranging n = 10 to 19.
References
[1] Measurement of Rydberg positronium fluorescence lifetimes. A. Deller, A. M. Alonso, B. S. Cooper,S. D. Hogan, and D. B. Cassidy. Phys. Rev. A 93, 062513 (2016).[2] Deceleration of supersonic beams using inhomogeneous electric and magnetic fields. S. D. Hogan,M. Motsch and F. Merkt, Phys. Chem. Chem. Phys. 13, 18705 (2011)[3] Selective Production of Rydberg-Stark States of Positronium. T. E. Wall, A. M. Alonso, B. S. Cooper,A. Deller, S. D. Hogan, and D. B. Cassidy. Phys. Rev. Lett. 114, 173001 (2015).[4] Electrostatically Guided Rydberg Positronium. A. Deller, A. M. Alonso, B. S. Cooper, S. D. Hogan,and D. B. Cassidy. Phys. Rev. Lett. 117, 073202 (2016)[5] Velocity selection of Rydberg positronium using a curved electrostatic guide. A. M. Alonso, B. S. Cooper,A. Deller, L. Gurung, S. D. Hogan, and D. B. Cassidy. Phys. Rev. A 95, 053409 (2017).[6] Muonic Hydrogen and the Proton Radius Puzzle. R Pohl, R Gilman, G A. Miller, and K Pachucki.Nucl. Part. Sci. 63 175 (2013).
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Tests of discrete symmetries in positronium decays
with the J-PET detector
P. Moskal 1 on behalf of the J-PET collaboration1. Institute of Physics, Jagiellonian University, Lojasiewicza 11, 30-348 Cracow
Positronium is the lightest purely leptonic object decaying into photons. As an atom bound by a centralpotential, it is a parity eigenstate, and as an atom built out of an electron and an anti-electron, it isan eigenstate of the charge conjugation operator. Therefore, the positronium is a unique laboratory tostudy discrete symmetries whose precision is only limited, in principle, by the effects due to the weakinteractions expected at the level of 10−14 [1] and photon-photon interactions expected at the level of10−9 [2]. Violation of T or CP invariance in purely leptonic systems has never been seen thus far [3].The experimental limits on CP and CPT symmetry violation in the decays of positronium are set at thelevel of 10−3 [4,5]. Thus, there is still a range of six order of magnitude where the phenomena beyond theStandard Model can be sought for by improving the experimental precision in investigations of decays ofpositronium atoms.The newly constructed Jagiellonian Positron Emission Tomograph (J-PET) is the first PET tomographbuilt from plastic scintillators [6-11]. As a detector optimised for the registration of photons from theelectron-positron annihilations, it also allows to perform tests of discrete symmetries in decays of positro-nium atoms via the determination of the expectation values of the discrete-symmetries-odd operators,which may be constructed from the spin of ortho-positronium atom and the momenta and polarizationvectors of photons originating from its annihilation [12,13,14]. In the talk we will present the capabilityof the J-PET detector to improve the current precision of testing CP, T and CPT symmetries in thedecays of positronium atoms and report on the first data-taking campaigns. With respect to the previousexperiments performed with crystal-based detectors, J-PET built of plastic scintillators, provides superiortime resolution, higher granularity, lower pile-ups, and opportunity to determine photon’s polarizationthrough the registration of primary and secondary Compton scatterings in the detector. These featuresmakes J-PET capable of improving present experimental limits in tests of discrete symmetries in decaysof positronium atom (a purely leptonic system).
References
[1] M. Skalsey, J. Van House, Phys. Rev. Lett. 67, 1993 (1991).[2] B. K. Arbic et al., Phys. Rev. A 37, 3189 (1988); W. Bernreuther et al., Z. Phys. C 41, 143 (1988).[3] V.A. Kostelecky and N. Russell, 2018 update to Rev. Mod. Phys. 83, 11 (2011).[4] T. Yamazaki, T. Namba, S. Asai, T. Kobayashi, Phys. Rev. Lett. 104, 083401 (2010).[5] P.A. Vetter, S.J. Freedman, Phys. Rev. Lett. 91, 263401 (2003).[6] J-PET: P. Moskal et al., Nucl. Instr. and Meth. A764, 31 (2014).[7] J-PET: P. Moskal et al., Nucl. Instr. and Meth. A775, 54 (2015).[8] J-PET: P. Moskal et al., Phys. Med. Biol. 61, 2025 (2016).[9] J-PET: L. Raczynski et al., Phys. Med. Biol. 62, 5076 (2017).[10] J-PET: M. Palka et al., Journal of Instrumentation 12, P08001 (2017).[11] J-PET: Sz. Niedzwiecki et al., Acta Phys. Polon. B48, 1567 (2017).[12] J-PET: P. Moskal et al., Acta Phys. Polon. B47, 509 (2016).[13] J-PET: A. Gajos et al., Nucl. Instr. and Meth. A819, 54 (2016).[14] J-PET: D. Kaminska et al., Eur. Phys. J C 76, 445 (2016).
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Recent progress in positronium experiments for
Bose-Einstein condensation
Akira Ishida1, Kenji Shu1, Tomoyuki Murayoshi1, ToshioNamba1, Shoji Asai1, Eunmi Chae2, Kosuke Yoshioka2, MakotoKuwata-Gonokami1, Nagayasu Oshima3, Brian E. O’Rourke3,
Koji Michishio3, Kenji Ito3, Kazuhiro Kumagai3, RyoichiSuzuki3, Shigeru Fujino4, Toshio Hyodo5, Izumi Mochizuki5 and
Ken Wada6
1. Department of Physics, Graduate School of Science, and International Center for ElementaryParticle Physics (ICEPP), the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
2. Photon Science Center (PSC), Graduate School of Engineering, the University of Tokyo, 7-3-1Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
3. National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba,Ibaraki 305-8568, Japan
4. Global Innovation Center (GIC), Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580,Japan
5. High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan6. National Institutes for Quantum and Radiological Science and Technology (QST), 1233 Watanuki,
Takasaki, Gunma 370-1292, Japan
Positronium (Ps), the bound state of an electron and its antiparticle positron, is the lightest and mostexotic hydrogen-like atom. Ortho-Ps is one of the best candidates for the first Bose-Einstein condensation(BEC) of any system which contains antimatter. Ps-BEC can be used to measure antimatter gravityusing an atomic interferometer. It can also be used as a source for a 511 keV gamma-ray laser. Ourtarget temperature and density to realize Ps-BEC is ∼ 10 K at ∼ 1017 cm−3. We proposed a new coolingscheme which is a combination of Ps thermalization and laser cooling [1,2]. A schematic view of theproposed experimental setup is shown in Fig. 1. The recent results and prospects of our experiments torealize Ps-BEC will be presented.
Figure 1: Conceptional view of the experimental setup. Positron bunches from a positron accu-mulator are injected into a cold silica cavity. Ps formed in the cavity is cooled by thermalizationand 243 nm lasers.
References
[1] K. Shu et al., J. Phys. B: At. Mol. Opt. Phys. 49, 104001 (2016).[2] K. Shu et al., J. Phys.: Conf. Ser. 791, 012007 (2017).
51
40
Observation of the hyperfine spectrum of
antihydrogen
T. Friesen 1
1. University of Calgary, Calgary, Alberta T2N 1N4, Canada.
Hyperfine spectroscopy of antihydrogen is one of the primary goals of the ALPHA experiment. Hydrogen’szero-field ground-state hyperfine splitting frequency has been measured to better than 1 part in 1012 [1].If we can reach a similar precision in antihydrogen it would provide an extremely precise test of CPTsymmetry. An initial proof-of-principle experiment in 2012 demonstrated our ability to excite positronspin resonance transitions in trapped ground state antihydrogen [2]. Recently, ALPHA performed animproved microwave spectroscopy experiment in which the response of antihydrogen atoms was probedover a much finer range of frequencies [3]. This experiment was able to measure the two positron spinflip transitions at the same magnetic field and determine the hyperfine splitting in antihydrogen to be1420.4± 0.5 MHz. I will present a detailed summary of that experiment and the tools we have developedto study antihydrogen’s hyperfine structure. I will also discuss recent improvements and the currentstatus of ALPHA’s hyperfine spectroscopy experiments.
References
[1] IEEE Trans. Instrum. Meas. IM-19, 200 (1970); Nature 229 110 (1970).[2] C. Amole et al. (ALPHA collaboration), Nature 483, 439 (2012).[3] M. Ahmadi et al. (ALPHA collaboration), Nature 548, 66 (2017).
52
41
Spectroscopy of the 1S − 2P transition of
antihydrogen
T. Momose1 for the ALPHA collaboration1. Department of Chemistry, and Department of Physics and Astronomy, The University of British
Columbia, Vancouver BC, Canada
While the hyperfine [1] and 1S − 2S transitions [2] in antihydrogen have been recently observed by theALPHA collaboration, the 1S−2P Lyman-alpha transition has a unique role to play. It will permit lasercooling of antihydrogen [3] to provide a cold and dense sample of antihydrogen for precision spectroscopyand gravity measurements. Challenges with the Lyman-alpha spectroscopy at 121.6 nm include the lackof convenient laser sources and optical components at these extremely short wavelengths. In order todetect the 1S − 2P transition of trapped antihydrogen, we have developed an all solid state nano-secondpulsed laser system at 121.6 nm. We will discuss details of the 121.6 nm laser system at CERN and willreport the status of the Lyman-alpha spectroscopy experiments with ALPHA.
References
[1] M. Ahmadi et al. (ALPHA collaboration), Nature, 548, 66 (2017).[2] M. Ahmadi et al. (ALPHA collaboration), Nature, 541, 506 (2017).[3] P.H. Donnan, M.C. Fujiwara and F. Robicheaux, J. Phys. B. 46, 025302 (2013).
53
42
Study of time reversal symmetry in the decay of
Ortho-Positronium atoms using J-PET
Juhi Raj1, Michal Silarski1 and Magdalena Skurzok1
On Behalf of the J-PET Collaboration
1. Jagiellonian University, Krakow, Poland
The Jagiellonian Positron Emission Tomograph (J-PET) is one of its kind based on organic scintillatorsbeing developed at Jagiellonian University in Krakow [1]. J-PET is an axially symmetric and highacceptance scanner that can be used as a multi-purpose detector system. It is well suited to pursuetests of discrete symmetries in decays of positronium in addition to medical imaging. Positronium is abound state of an electron and an anti-electron, and thus it is a purely leptonic object. This makes itideal for the studies of discrete symmetries in the leptonic sector [7]. The gamma quanta originatingfrom positronium decay interact in the plastic scintillators predominantly via the Compton effect [3][8].Decays of ortho-positronium atoms into three photons can be reconstructed in terms of time and spatialcoordinates of the decay using the trilateration-based method [2][3]. J-PET enables the measurement of
the momentum vector ~ki and the polarization vector ~εj of photons [7]. Measurement of polarization ofhigh energy photons (511 keV) is a unique feature of the J-PET detector which allows the study of timereversal symmetry violation by determining the expectation values of the time reversal symmetry oddoperator [7],
(~εj .~ki), (forj 6= i) (2)
So far, Time reversal symmetry violation have not been observed in purely leptonic systems. The bestexperimental upper limits for CP and CPT (C-Charge Conjugation, P-Parity and T-Time) symme-try violation in positronium decay is set to 0.3x10-3 [4] [5]. According to the standard model predic-tions, photon-photon interaction or weak interaction can mimic the symmetry violation in the order of10-9(photon-photon interaction) and 10-13 (weak interactions) respectively [9 - 11]. There is about 6orders of magnitude difference between the present experimental upper limit and the standard modelpredictions [6]. J-PET group aims to improve the sensitivity for the tests of the time reversal symmetrywith respect to the previous experiments in the leptonic sector.
References
[1] P. Moskal et al., Phys. Med. Biol. 61 (2016)[2] A. Gajos et al., Nucl. Instrum. Methods A 819, 54 (2016)[3] D. Kamiska et al. Eur. Phys. J. C 76, 445 (2016).[4] T. Yamazaki, T. Namba, S. Asai, T. Kobayashi, Phys. Rev. Lett. 104, 083401 (2010)[5] P.A. Vetter, S.J. Freedman, Phys. Rev. Lett. 91, 263401 (2003)[6] V.A. Kostelecky and N. Russell, January 2018 update to Reviews of Modern Physics 83, 11(2011)[7] P. Moskal et al., Acta Phys. Polon. B 47, 509 (2016)[8] P. Moskal et al., Nucl. Instr. and Meth. A 764 (2014) 317-321[9] M. S. Sozzi, Discrete Symmetries and CP Violation. From Experiment to Theory, Oxford UniversityPress (2008).[10] W. Bernreyther et. al., Z. Phys. C 41, 143 (1988)[11] B. K. Arbic et. al., Phys. Rev. A 37, 3189 (1988)
54
43
Accelerators Validating Antimatter Physics
Welsch CarstenUniversity of Liverpool
The Extra Low Energy Antiproton ring (ELENA) will be a critical upgrade to the unique AntiprotonDecelerator facility at CERN and is currently being commissioned. ELENA will significantly enhancethe achievable beam quality and enable new experiments.To fully exploit the discovery potential of this facility, advances are urgently required in numerical toolsthat can adequately model beam transport, life time and interaction, beam diagnostics tools and detectorsto fully characterize the beam’s properties, as well as in novel experiments that exploit the enhanced beamquality that ELENA will provide. These three areas form the scientific work packages of the new pan-European research and training initiative AVA (Accelerators Validating Antimatter physics). The projecthas received around 4M of funding from the European Union and brings together universities, researchcenters and industry to train 15 Fellows through research in this area.This contribution gives an overview of the AVA research programme across it’s three scientific workpackages. It also shows the upcoming events which AVA will organise for the wider antimatter researchcommunity.
55
Talks
Friday 16th
56
44
Recent BABAR results on CP violation
Sandrine Emery-Schrenk 1 on behalf of the BABAR collaboration1. IRFU/DPhP, CEA centre de Saclay, F-91191 Gif-sur-Yvette cedex, FRANCE
This review talk covers recent results of the BABAR experiment on CP violation in the quark sector. Itincludes the recent measurement, using BABAR and Belle data, of cos(2β) = cos(2φ1) in B0 → D(∗)h0
with D → K0Sπ
+π− decays, using a combined time-dependent Dalitz plot analysis. The analyses use thedata sets of the BABAR and Belle experiments containing 471×106 and 772×106 BB pairs collected at theΥ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively.
57
45
Single-photon laser spectroscopy of cold antiprotonic
helium
Masaki HoriMax-Planck-Institut fur Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany
The Atomic Spectroscopy and Collisions Using Slow Antiprotons (ASACUSA) collaboration is carryingout precise laser spectroscopy experiments on antiprotonic helium (pHe+ ≡ p+ He2+ + e−) atoms [1,2].Employing buffer-gas cooling techniques in a cryogenic gas target, samples of atoms were cooled totemperature T = 1.5–1.7 K, thereby reducing the Doppler width in the single-photon resonance lines[3]. By comparing the results with three-body quantum electrodynamics calculations, the antiproton-to-electron mass ratio was determined as Mp/me = 1836.1526734(15). Further improvements in theexperimental precision are currently being attempted.
References
[1] V.I. Korobov, L. Hilico, J.-P. Karr, Phys. Rev. Lett. 112, 103003 (2014).[2] V.I. Korobov, L. Hilico, J.-P. Karr, Phys. Rev. A 89, 032511 (2014).[3] M. Hori et al., Science 371, 610 (2016).
58
46
Constraints for fundamental short-range forces from
the neutron whispering gallery, and extention of this
method to atoms and antiatoms
V.V. Nesvizhevsky1 and A.Yu. Voronin2
1. Institut Max von Laue - Paul Langevin, 71 avenue des Martyrs, Grenoble, France, 380002. Lebedev Institute, 53 Leninski pr., Moscow, Russia, 119991
Extra fundamental short-range interactions mediated by new bosons are predicted in many extensionsof the Standard Model of particle physics. They are also predicted in theories with large extra spatialdimentions and theories involving the light dark matter hypothesis.To search for such interactions at different charateristic distances, the experimentalists use many methodsincluding measurements of gravitational interaction at short distances, the search for extra interactions ontop of the van der Waals/Casimir-Polder interaction, the search for rare proceeses in neutrino detectors,precision measurements with atoms, molecules and neutrons. Comparison of the sensitivities of differentexperiments to extra short-range forces in the standard Yukawa parametrization is published, for example,in ref. [1].A competitive method of searching at characteristic distances of about 10 nm is the precision measurementof the neutron whispering gallery [2]. This phenomenon is analogous to the well-known phenomenon ofthe whispering gallery of electromagnetic waves of a broad frequency range, as well as the sound wave.However, a material wave, for example a neutron wave, provides an additional possibility due to theexistence of a nonzero neutron mass: for a neutron, the energy values of the whispering-gallery quantumstates depend on the mass of the neutron and the interactions of this mass with the surface. Moreover,the neutron in such quantum states is localized at a distance from the surface of the order of tens ofnanometers. Even a tiny extra force between the neutron and the surface at such distances would leadto a measurable shift in the energy of whispering-gallery quantum states.We present the results of experiments performed with cold neutrons and estimate their sensitivity toextra short-range forces. We affirm that this method can also be extended to experiments with atomsand antiatoms [3]. The sensitivity of atomic experiments may be even higher than thus providing asimilar, or even higher than the sensitivity of neutron experiments. More details could be found in [4].
References
[1] I. Antoniadis et al, Compt. Rend. Phys. 12, 755 (2011).[2] V.V. Nesvizhevsky et al, Nature Phys. 6, 114 (2010).[3] A.Yu. Voronin, V.V. Nesvizhevsky and S. Reynaud, Phys. Rev. A 85, 014902 (2012).[4] V.V. Nesvizhevsky and A.Yu. Voronin, Surprising Quantum Bounces, Imperial College Press, London,UK (2015).
59
47
Laser cooled anions as a sympathetic coolant for
antiprotons
J. Fesel1, S. Gerber1, M. Doser1, D. Comparat2
1. CERN, European Laboratory for Particle Physics, 1211 Geneva, Switzerland Daniel2. Laboratoire Aime Cotton, CNRS, Universite Paris–Sud, ENS Paris Saclay, Universite Paris–Saclay,
Batiment 505, 91405 Orsay, France
Several ongoing experiments at CERN aim at testing the CPT theorem and the weak equivalence principleusing antimatter, among them the AEgIS experiment. For the latter, antiprotons inside a Penningtrap interacting with Rydberg positronium form antihydrogen, which will then be used for precisionmeasurements. The achievable sensitivity of these measurements is determined by the antihydrogentemperature which, for this production scheme, is determined by the temperature of the antiprotons.Two schemes relying on the use of laser-cooled anionic molecules to sympathetically cool antiprotonsconfined in the same trapping potential are under investigation, one relying on La- ions, and one on C2-molecules. After a short overview of both approaches, the focus will be put on a test setup to producecold ground state C2- molecules that is currently being commissioned. This setup will be presented,together with a theoretical study on the feasibility of several laser cooling schemes, including one usingthe AC-Stark shift.Laser cooling of anions — which has so far never been achieved — would also enable the sympatheticcooling of any other negatively charged species, opening new opportunities in a variety of research areas.
References
[1] Yzombard, P. et al., Phys. Rev. Lett., 114, 213001 (2015)[2] Fesel, J. et al., Phys. Rev. A, 96, 31401 (2017)[3] S. Gerber et al., New J. Phys. in press (2018) https://doi.org/10.1088/1367-2630/aaa951
60
48
Positronium and Muonium two photon laser
spectroscopy
P. Crivelli 1
1. ETH Zurich, Institute for Particle Physics and Astrophysics, 8093 Zurich, Switzerland.
Positronium and muonium, being purely leptonic, are very interesting systems to test bound state QEDfree of finite size effects and hadronic corrections [1]. They are also very sensitive probes to search forNew Physics [2] and can be used to extract fundamental constants such as the muon mass and magneticmoment [3].In this talk, we report the current status of the ongoing experiment at ETH Zurich [4] aiming to improvethe accuracy on the 1S-2S transition frequency of positronium in order to cross check the latest QEDcalculations [5]. We will present some preliminary results including the technique we developed to correctfor the second order Doppler shift, the main systematic uncertainty in this experiment.We will show that with the recent advances in UV laser technology, our novel cryogenic muonium convert-ers and the detection techniques we developed for positronium spectroscopy, a 1000-fold improvement inthe determination of the same transition in muonium compared to the current results [6] will be possibleusing the LEM beamline at PSI. This will provide the best determination of the muon mass at the 1 pptlevel. It can also be used to extract the muon g-2 from the ongoing experiment at Fermilab which have aprojected accuracy of 0.1 ppm [7] . In fact at this level, the comparison with the theoretical value will belimited by the current knowledge of the muon magnetic moment or the muon mass. Moreover, by usingthe expected results of the ongoing hyperfine splitting measurement of muonium in Japan at JPARC [8],it will provide one of the most sensitive tests of bound-state Quantum Electrodynamics. It will also allowto determine the Rydberg constant free from nuclear and finite-size effects at a level of 10−12 which isinteresting in light of the proton charge radius puzzle [9] and provide a new determination of the finestructure constant at a level of 1 ppb. This has to be compared with the electron g-2 experiment atHarvard (0.24 ppb) [10] and the Rubidium experiment at Laboratoire Kastler Brossel (0.62 ppb) [11].
References
[1] S.. Karshenboim,Phys. Rep. 422, 1 (2005). [2] see e.g. L. Willmann et al., Phys. Rev. Lett. 82, 49(1999); A. Badertscher et al., Phys. Rev. D 75, 032004 (2007). [3] P. J. Mohr, D. B. Newell and B. N.Taylor, Rev. Mod. Phys. 88, 035009 (2016). [4] D. Cooke et al., Hyperfine Int. 233, 67 (2015). [5] G.S. Adkins et al., Phys. Rev. Lett. 115 233401 (2015) and references therein [6] V. Meyer et al., PhysRev. Lett. 84, 1136 (2000). [7] W. Gohn, FERMILAB-CONF-17-602-PPD, arXiv:1801.00084 [hep-ex].[8] P. Strasser et al., Hyperfine Interact. 237, 124 (2016). [9] R. Pohl et al., Nature 466, 213 (2010); A.Antognini et al., Science 339, 417 (2013). [10] B. Rym et al., Phys. Rev. Lett. 106 080801 (2010). [11]D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev. Lett. 100, 120801 (2008).
61
49
Production of cold muonium for future atomic
physics and gravity experiments
A. Antognini1,2, P. Crivelli1, K. Kirch1,2, D. Taqqu1, M. Bartkowiak2, A. Knecht2, N. Ritjoho2,D. Rousso2, R. Scheuermann2, A. Soter2, M. F. L. De Volder3, D. M. Kaplan 4, T.J. Phillips 4
1 Institute for Particle Physics and Astrophysics, ETH Zurich, 8093 Zurich, Switzerland2 Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland3 Department Of Engineering, University of Cambridge,
17 Charles Babbage Road, Cambridge, UK4 Illinois Institute of Technology, Chicago, IL 60616 USA
We are investigating methods to create a novel muonium (Mu) source, based on µ+ → Mu conversionin superfluid helium (SFHe), which has the potential of providing high brightness Mu beams for nextgeneration laser spectroscopy experiments. We are also investigating the feasibility of using such sourcesfor measuring the gravitational interaction of Mu. The positive muon (µ+) which is dominating the Mumass is not only an elementary antiparticle, but a second-generation lepton too. This makes a gravityexperiment highly motivated [1], and complementary to gravitational studies of antihydrogen [2,3,4] andpositronium [5].State-of-the-art Mu sources (like silica aerogel, mesoporous SiO2) emit Mu atoms with a large (thermal)energy distribution, and wide (∼ cos θ) angular distribution. Cooling of these porous samples below100 K results in rapidly declining numbers of vacuum-emitted muonium due to decreased mobility, andatoms sticking to the pore walls [6].Our proposed method relies on stopping µ+ in a thin layer of SFHe, and forming Mu by capturing anelectron from the ionization trail. A fraction of the Mu diffuses to the SFHe surface within their lifetime,where emission into vacuum occurs. The velocity of the emitted Mu (∼ 6 mm/µs) is given by theirlarge chemical potential (E/kB ∼ 270 K) in SFHe, while the low temperature of the liquid (T < 0.3 K)determines their transverse momentum [7].In this talk, methods and challenges to create such SFHe Mu sources, the present status of the experimentin PSI, and the feasibility of an antimatter gravity experiment will be discussed.
References
[1] Kirch, K. et al. In International Journal of Modern Physics: Conference Series 30 1460258 (WorldScientific, 2014)[2] Charman, A. et al. (Collaboration ALPHA). Nature Communications 4, 1785 (2013)[3] Scampoli, P. and Storey, J. Modern Physics Letters A 29, 1430017 (2014)[4] Perez, P. and Sacquin, Y. Classical and Quantum Gravity 29, 184008 (2012)[5] Cassidy, D. and Hogan, In International Journal of Modern Physics: Conference Series, 30, 1460259(World Scientific, 2014)[6] Antognini, A. et al. Physical Review Letters 108, 143401 (2012)[7] Taqqu, D. Physics Procedia 17, 216 223 (2011)
62
63
Posters
Tuesday 13th and Thursday 15th
64
1
High sensitivity search for Pauli-forbidden atomic
transitions at the LNGS underground laboratory
J. Marton1 et al. (VIP2 Collaboration)1. Stefan Meyer Institute, Boltzmanngasse 3, 1090 Vienna, Austria
The Pauli Exclusion Principle (PEP) and its connection to the spin-statistics theorem in fermionic systemsrepresent a cornerstone of physics. However, from theoretical considerations there are speculations aboutpossible violations in the lepton sector, i.e. for neutrinos, which would have severe consequences forcosmology. There were numerous attempts to attack experimentally the validity of the Pauli ExclusionPrinciple which are based on different assumptions and experimental methods. We conducted a verysuccesful experiment VIP [1] which improved the limit for violation avoiding the Greenberg-Messiahsuperselection rule. In the current experiment VIP2 [2,3] at the Gran Sasso Laboratory (LNGS-INFN)we are want to further improve the limit of the validity of PEP for leptons by searching PEP-forbiddenelectron transitions in a high-sensitivity experiment. First results show that we can expect to reach alimit in the range of 10−31. The underlying concept of the experiment, preliminary results and an outlookfor the next stages of VIP2 will be given.
Figure 1: Inner part of the VIP2 apparatus with the copper foil, the X-ray detection systemand part of the active shielding.
References
[1]S. Bartalucci et al.,Physics Letters B 641(1):1822, 2006.[2]C. Curceanu et al., Entropy 2017, 19(7), 300: doi:10.3390/e19070300[3]J. Marton et al., Journal of Physics: Conference Series, 631(1):012070, 2015.
65
2
AD infrastructures and experimental areas
evolutions in the context of ELENA development
Francois ButinCERN, 1211 Geneva 23, Switzerland *E-mail: [email protected]
With the ongoing installation of the ELENA machine in the CERN AD facility, the AD infrastructuresmust be adapted to cope with another 20 years of exploitation of the facility with improved conditionsfor most experiments.The first stages of improvements have been completed up to 2017 and the next stages of evolutions will bereviewed, detailing the enlargement of some existing experimental areas, installation of new experimentalareas, maximization of usage of AD ground floor space for physics and AD facility consolidation program.
66
3
Models of nn transition in medium
Valeriy I.NazarukInstitute for Nuclear Research of RAS, 60th October
Anniversary Prospect 7a, 117312 Moscow, Russiae-mail: [email protected]
Abstract
The basic problems of the models of nn transition in medium and nuclei arediscussed. The lower limits on the free-space nn oscillation time obtained by meansof various models are considered.
67
4
Proton and neutron electromagnetic form factor and
charge radius in lattice QCD
Eigo Shintani (PACS collaboration)RIKEN Advanced Institute for Computational Science, Kobe, Hyogo 650-0047, Japan
In this talk, we present the recent lattice QCD study of elemctromagnetic form factor in the low energyscale, Q2 ≈ 0.02 GeV2, using large box, L3 > 8 fm3 in the physical point. We non-perturbatively computethe electromagnetic form factor (Sachs form factor, GE(Q2) and GM (Q2)) as Q2-dependence for neutronand proton, and perform the theoretical calculation of charge radius,
〈r2E〉 = −6
d
dQ2GE(Q2)
∣∣∣Q2=0
, (3)
from the first principle of QCD. Our study is directly comparable with experimental measurement ofcharge radius, and which can provide the theoretical information for “charge radius puzzle”.As a by-product, we also compute the axial and pseudo-scalar form factor as Q2-dependence on the samegauge ensemble. This is used to estimate the axial-charge radius in lattice QCD, and we then comparethose results with experimental measurement.
68
5
Antihydrogen production using directly injected
antiprotons with reduced energy spread in
ASACUSA
M.Tajima1, N.Kuroda2, C.Amsler3, H.Breuker4, P.Dupre4,M.Fleck3, H.Higaki5, Y.Kanai1, B.Kolbinger3, M.Leali6,7,V.Mackel3, C.Malbrunot3,8, V.Mascagna6,7, O.Massiczek3,
Y.Matsuda2, Y.Nagata9, B.Radics41, M.C.Simon3, S.Ulmer4,L.Venturelli6,7, E.Widmann3, Y.Yamazaki4, J.Zmeskal3
1. Nishina Center for Accelerator-Based Science, RIKEN, Saitama 351-0198, Japan2. Institute of Physics, The University of Tokyo, Tokyo 153-8902, Japan
3. Stefan-Meyer-Institut fur Subatomare Physik, Osterreichische Akademie der Wissenschaften,Boltzmanngasse 3, 1090 Wien, Austria
4. Ulmer Fundamental Symmetries Laboratory, RIKEN, Saitama 351-0198, Japan5. Graduate School of Advanced Sciences of Matter, Hiroshima University, Hiroshima 739-8530, Japan
6. Dipartimento di Ingegneria dell’Informazione, Universita di Brescia, Brescia 25133, Italy7. Istituto Nazionale di Fisica Nucleare, Sez. di Pavia, 27100 Pavia, Italy
8. Experimental Physics Department, CERN, Geneve 23, 1211, Switzerland9. Department of Physics, Tokyo University of Science, 162-8601 Tokyo, Japan
The ASACUSA collaboration is developing an apparatus and methods to measure the ground-state hyper-fine splitting of antihydrogen using a spin-polarized atomic beam [1]. Antihydrogen atoms are producedin a cusp magnetic field whose gradients focus or defocus their trajectories depending on their magneticmoment [2]. We have succeeded in producing antihydrogen atoms in the cusp field [3] and in detectingthem in the magnetic-field-free region at 2.7 m downstream of the production region [4]. Antiprotonswere injected from the antiproton accumulator MUSASHI into a pre-loaded positron plasma in order toproduce antihydrogen, which is called direct injection method. For realization of the spectroscopy, theantihydrogen beam should be cold and its intensity should be as high as possible. As one possibility ofutilizing the direct injection method, the injection scheme of antiprotons had been improved to avoidheating of the positron plasma as discussed in [5]. We report further improvement on the energy spreadof antiprotons directly measured at the cusp trap and observation of a high antihydrogen productionrate at the timing of the antiproton injection. Recent developments of other mixing schemes will also bediscussed briefly.
References
[1] A.Mohri and Y.Yamazaki, Europhysics Letters, 63(2), 207 (2003).[2] Y.Nagata and Y.Yamazaki, New J. Phys., 16, 083026 (2014).[3] Y.Enomoto et al., Phys. Rev. Lett., 105, 243401 (2010).[4] N.Kuroda et al., Nat. Commun., 5, 3089 (2014).[5] M.Tajima et al., JPS Conference Proceedings, 18, 011008 (2017)
1Current address: Institute for Particle Physics, ETH Zurich, Zurich CH-8093, Switzerland.69
6
Charge exchange three-body reaction in the presence
of a laser field
Kevin Leveque, Paul-Antoine HervieuxUniversite de Strasbourg, CNRS, IPCMS UMR 7504, F-67000 Strasbourg, France
In order to make a direct observation of the effect of gravitation on antimatter, the GBAR [1] experimentaims at measuring the influence of Earth’s gravity in the trajectory of antihydrogen atoms. The firststep of the experiment involves two successive low energy collisions. Indeed, the antihydrogen ions willbe produced in two steps. The first one is the charge exchange three-body reaction (1): p + Ps(np) →H(nh)+e− where p stands for antiproton, Ps(np) for positronium (bound positron-electron pair) either inground state (np = 1) or in an excited state (np = 2), H(nh) for antihydrogen (which can be also producedin an excited state nh 6= 1) and e− for electron. The second one is a more complex four-body reaction(2): H(nh) + Ps(np)→ H+ + e−, in which the antihydrogen produced in the first reaction interacts withanother positronium to create an antihydrogen ion.In this contribution we explore the possibility to increase significantly the antihydrogen positive ionproduction rate by assisting the capture processes involved in the three-body reaction (1) using a laserfield having standard specifications (other than that used to excite the positronium). By using a formalismadapted from [2-4], we present an extensive study of the influence of the laser parameters (laser fieldstrength and photon energy) on the charge exchange cross-sections in the energy range of interest for theGBAR’s experiment. Under special conditions the antihydrogen atom formation cross sections may beenhanced by the presence of the laser field (cf. Figure 1).
4 6 8 10
15
20
25
30 ε0 = 107 V/cm
ε0 = 0
σ (π
a2 0 )
Ep (keV)
Figure 1: Cross section of the reaction p + Ps(1s) → H(nh = 2) + e− as a function of theantiproton energy. Solid line: laser off; Dashed line: laser on with an electric field strength of107 V.cm−1 corresponding to I = 7.2× 1011 W.cm−2.
References
[1] GBAR Collaboration, CERN Report No. SPSC-P-342, (2011).[2] P. Comini, P. -A. Hervieux, New J. Phys. 15, 09022 (2013).[3] P. Martin, V. Veniard, A. Maquet, P. Francken and C. J. Joachain, Phys. Rev. A 39, 6178 (1989).[4] Atoms in intense laser fields, C. J. Joachain, N. J. Kylstra, R. M. Potvliege, Cambridge UniversityPress (2012).
70
7
Gravitational and matter-wave spectroscopy of
atomic hydrogen at ultra-low energies
Sergey VasilievDepartment of Physics and Astronomy, University of Turku, 20500 Turku, Finland 1
We propose an experimental study of atomic hydrogen gas at ultra-low temperatures T < 100µK whenthe thermal energy of atoms is comparable with the changes of their potential energy in the Earthgravity field. At these conditions we are going to implement a gravitational spectroscopy for studies ofquantum properties of ultra-cold atomic hydrogen and its interactions with matter and gravity, similarto experiments with ultra-cold neutrons [1,2]. We are going to build a magnetic trap for cooling a largenumber of H atoms below 1 mK, possibly reaching conditions for the the Bose-Einstein Condensation[3]. We will release ultra-slow atoms from the trap onto the cold surface of superfluid helium. Owing tothe weakest interaction potential such surface provides nearly perfect reflecting conditions for low-energyatoms. This will allow studies of quantum bounces and stationary gravitational states of H atoms inthe potential well created by this surface and the field of Earth gravity. The methods and ideas of thisproject may be useful for making similar experiments with antihydrogen which are currently prepared inCERN.
References
[1] Valery V. Nesvizhevsky et al., Nature 415, 297 (2002).[2] V.V. Nesvizhevsky et. al., Phys. Rev. D 67, 102002 (2003).[3] Dale G. Fried et al., Phys. Rev. Lett. 81, 4545 (1998).
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8
Beam Emittance Studies of Electron Cooling in
ELENA
B. Veglia1,2, J. R. Hunt1,2, J. Resta-Lopez1,2, V. Rodin1,2
and C. P. Welsch1,2
1. The University of Liverpool, Liverpool, United Kingdom2. The Cockcroft Institute, Sci-Tech Daresbury, Warrington, United Kingdom
The Extra Low ENergy Antiproton storage ring (ELENA) will provide high quality beams for antimatterexperiments, decelerating antiprotons to a kinetic energy of 100 keV. At such low energies, it is importantto correctly evaluate the long term beam stability.To provide a consistent explanation of the differentphysical phenomena affecting the beam, tracking simulations have been performed and the results arepresented in this contribution. These include electron cooling simulations in the presence of variousscattering effects. The impact of several imperfections in the electron cooling process on the beamquality are also discussed. In addition, analytical approximations of the temporal variation of emittanceunder these conditions are compared with numerical simulation results.
72
9
Development of TOF detector in GBAR experiment
B.H.Kim1, J.W.Hwang1, A.Lee1, J.Lee2 and S.K.Kim1
1. Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea2. Institute for Basic Science, Daejeon, 34126, Korea
GBAR (Gravitational Behavior of Antihydrogen at Rest) experiment aims to measure the free fall ac-celeration of anti-Hydrogen atom in the terrestrial gravitational field. As one of main detection system,Time-Of-Flight (TOF) detector has been prepared to measure free-fall time of anti-Hydrogen by detectingsecondary particles from the annihilation of anti-Hydrogen. TOF is composed of 44 long plastic scintil-lation bars surrounding 4 side of free fall chamber. The TOF design is optimized to measure secondaryparticles from annihilation and to distinguish cosmic ray background from the signal. We achieve the timeresolution better than 100ps enough to distinguish the annihilation signal at the top of free-fall chamberfrom the cosmic ray background. We present the design of TOF, the time and the spatial resolutionmeasured by cosmic ray and the results of simulation study based on GEANT4.
73
10
Towards sympathetic cooling and manipulation of
single (anti-)protons by atomic ions in a double-well
Penning trap
Juan M. Cornejo1, Malte Niemann1, Johannes Mielke1, TeresaMeiners1, Anna-Greta Paschke1, Jonathan Morgner1, Matthias
Borchert1,3, Amado Bautista-Salvador1,2, Stefan Ulmer3 andChristian Ospelkaus1,2
1. Institut fur Quantenoptik, Leibniz Universitat Hannover, 30167 Hannover, Germany2. Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
3. Ulmer Fundamental Symmetries Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
High-precision experiments using (anti-)protons in Penning traps are an excellent system to implementa precise test of CPT invariance with baryons (see e.g. [1,2]). The current experiments are based onimage current detection and the continuous Stern-Gerlach effect, where particle cooling and detectionare performed by means of tuned LC-circuits. Here we present an alternative approach to these experi-ments using quantum logic inspired cooling and readout techniques based on a proposal by Heinzen andWineland [3,4], which will allow to overcome current technical limitations linked to the finite temperatureof (anti-)protons as well as speeding up the spin state detection [5]. For this purpose, a single laser-cooled9Be+ ion will be used for sympathetic cooling and detection of single (anti-)protons employing an ad-vanced cryogenic Penning trap system with a double-well potential. This experimental concept is underdevelopment with protons at Hanover and will be implemen! ted with antiprotons at CERN withinthe BASE collaboration [6]. In this contribution, the experimental setup will be presented showing thestatus of the project, focusing on the trap geometry and associated infrastructure, as well as the nextsteps towards a microtrap-based double well potential for increasing coupling and loading of protons. Weacknowledge funding by ERC StG QLEDS and DFG through SFB CRC 1227 DQ-mat, project B06.
References
[1] S. Ulmer et al., Nat. 524, 196 (2015).[2] C. Smorra et al., Nat. 550, 371 (2017).[3] D.J. Heinzen et al., Phys. Rev. A 42, 2977 (1990).[4] D.J. Wineland et al., Natl. Inst. Stand. Technol. 103, 259 (1998).[5] A. Mooser et al., Phys. Rev. Lett. 110, 140405 (2013).[6] C. Smorra et al., Eur. Phys. J. Spec. Top. 224, 3055 (2015).
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11
Positronium decay study with the J-PET detector
K. Dulski1 on behalf of the J-PET collaboration1. Institute of Physics, Jagiellonian University, Lojasiewicza 11, 30-348 Cracow
Jagiellonian Positron Emission Tomography (J-PET) is a first PET tomograph built from plastic scintilla-tors [1-4]. As a detector optimised for the registration of photons from the positron-electron annihilationit is also used for the studies of the decays of positronium atoms [5-7].
In this poster we will present: (i) results of the commissioning of the J-PET detector, (ii) methodsof the data selection and analysis, and (iii) first lifetime spectra of positronium (produced in the porouspolymer [8]) measured with the J-PET detector.
References
[1] P. Moskal et al., Nucl. Instr. and Meth. A764 317, (2014)[2] P. Moskal et al., Nucl. Instr. and Meth. A775 54, (2015)[3] P. Moskal et al., Phys. Med. Biol. 61 2025, (2016)[4] Sz. Niedzwiecki et al., Acta Phys. Polon. B48 1567, (2017)[5] P. Moskal et al., Acta Phys. Polon. B47 509, (2016)[6] A. Gajos et al., Nucl. Instr. and Meth. A819 54, (2016)[7] D. Kaminska et al. Eur. Phys. J C 76, (2016)[8] B. Jasinska et al., Acta Phys. Polon. B47 453,(2016)
75
12
Detection of charged particle, non neutral plasma,
antihydrogen and positronium in AEgIS
Mattia Fanı1(on behalf of the AEgIS Collaboration)
1. CERN, INFN Sezione di Genova and Universita di Genova
The main scientific goal of the AEgIS experiment [1] is the direct measurement of the Earth’s localgravitational acceleration g on antihydrogen (H). The weak equivalence principle is a foundation of Gen-eral Relativity. It has been extensively tested with ordinary matter but very little is known about thegravitational interaction between matter and antimatter. Antihydrogen is to be produced in AEgIS viacharge exchange reactions between Rydberg-excited positronium and cooled down antiprotons [2]. Sev-eral detection techniques are extensively used to monitor antiproton and positron manipulations towardsthe antihydrogen formation inside the main apparatus. Positronium detection techniques underwentimportant improvements in sensistivity during last year and the detector dedicated to antihydrogen de-tection underwent upgrades and in-depth commissioning. An improvement of the antihydrogen detectionefficiency is provided by incorporation of external scintillators into the expanded detection scheme, de-veloped, tested and set up for the next data taking period.
References
[1] G. Drobychev et al., CERN-SPSC-2007-017, http://cdsweb.cern.ch/record/1037532 (2007).[2] M. Doser et al., Classical and Quantum Gravity 29(18):184009 (2012).
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13
ON THE POSSIBILITY OF FORMATION OF
EXOTIC PARTICLES AT THE CHANNELING OF
LOW ENERGY ANTIPROTONS IN LiH CRYSTAL
M.V. Maksyuta1, V.I. Vysotskii1 and S.B. Dabagov2
1. Taras Shevchenko Kyiv National University, Kyiv, Ukraine2. Lab. Naz. di Frascati, Frascati, Italy
As an alternative to the traditional methods of exotic particles creation (see, for example [1]) in [2] itwas proposed for the first time to generate protonium atoms pp by proton capture in a LiH crystalby channeling of low energy antiprotons using nonstationary perturbation theory. In this paper, thepossibility of generation of exotic protonium atoms pp (as well as antiprotonic lithium ions pLi+) inthe same crystal is proposed to be considered within the framework of the theory of sudden perturba-
tions. Based on the quantum states ψ ′±(r ′) =(2πu2
±)−3/4
exp(−r ′ 2/4u2
±)
of Li+ and H− ions, where
u± are the amplitudes of their thermal oscillations, the amplitudes of the probabilities A(±)n (ρ, n) =∫
ψ ′±(r ′)ψn00(|~r − ~r ′|) exp(−iM±v(~r ′ · ~ez)/})d~r ′ (here M± are the masses of Li+ and H− nuclei, v isantiproton velocity) of Li+ ions and protons capture into the quantum state ψn00(r) [3] of the antiprotonare calculated (instead of the Bohr radius a0 we take a0/918). After averaging over the transverse coordi-nate ~ρ of the antiproton, channeled at zero angle relative to [110] axis of the LiH crystal, the probabilities
W(±)n (v) of the appearance of antiprotonic lithium ions pLi+ and protonium atoms pp are calculated.
Plots of functions ζ(±)n (v) = W
(±)n (v)/W
(±)n (0), for example, for n = 1 (dashed curve) and n = 5 (solid
curve) are shown in the figures below.
Figure 1: Plots of the probabilities of the appearance (in relative units) of exotic particles pLi+
- (a) and pp - (b) at the channeling of low energy antiprotons in LiH crystal.
It is clear from this consideration that the probability of the appearance of antiprotonic lithium ions isabout an order of magnitude higher than that of protonium atoms, but this occurs at lower velocities. We
also note that the resonance character of dependences ζ(±)n (v) does not change significantly with increase
of n, but lead to decrease of the probabilities decrease.
References
[1] E. Klempt, F. Bradamante, J.-M. Richard, Phys. Rep. 368, 119 (2002).[2] N.V. Maksyuta, V.I. Vysotskii, S.B. Dabagov, Nucl. Instrum. Methods B 402, 232 (2017).[3] A.S. Davydov, Quantum Mechanics, Pergamon Press (1965).
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14
DESCRIPTION OF THE TRANSMUTATION OF
ELEMENTARY PARTICLES USING THE
THEORY OF KNOTS
M.V. MaksyutaTaras Shevchenko Kyiv National University, Kyiv, Ukraine
It is known that the theory of knots has already been applied in physics for a long-time (see, for example,[1]). In the work [2] four families of fermions with the right and the left trefoils oriented are associated.In this paper electrons and positrons also are associated with the knots of right (K−) and left (K+)trefoils (see the Figure 1), for which the Jones polynomials are respectively equal V (K−) = q + q3 − q4
and V (K+) = q−1 + q−3 − q−4 [1].
Figure 1: Image of the knots of the right (K−) and the left (K+) trefoils.
In [2] knots for four massless vector bosons, which in different combinations are connected sums of linksK− and K+ are also proposed. For example, a vector W− boson can be associated with a knot KW− =K−]K−, for which the Jones polynomial in accordance with theorem in [3], is equal V (KW−) = V 2(K−).Further, in this paper it is emphasized that using theory of knots it is possible to describe the decayprocesses of elementary particles if we use the property of Jones polynomials for the disconnected sumof knots, namely V (K1 tK2) = −V (K1)V (K2)(q1/2 + q−1/2) [3]. Applying this property to one of thedecay channels W− → e− + e− + νe (see, for example, [4]), we find the Jones polynomial V (Kνe) =(q1/2 + q−1/2)−2 for the electron antineutrino νe. It is obvious that an analysis based on the theory ofknots can also be applied to many other transmutations of elementary particles.In conclusion, we note that this mathematical description of elementary particles by means of knots(knotted strings) can also give some physical interpretation. As it is stated in [5], two vacuums can beconstructed from right and left trefoils, namely a vacuum of dark matter with Plank energy density anda physical vacuum of the surrounding space with zero energy density. If such consideration is correct,than we can assume that at Planck distances there should exist energy flows with the topology of openand knotted strings, which are compared with elementary particles.
References
[1] M. Atiyah, The geometry and physics of knots, Cambridge University Press (1990).[2] R.J. Finkelstein, A.C. Cadavid, arXiv:hep-th/0507022v2, 26 Oct. (2005).[3] V.O. Manturov, Theory of knots, Moscow-Izhevsk: NITS Regular and Chaotic dynamics (2005).[4] G. Kane, Modern elementary particle physics, Addison-Wesley Publishing Company, Inc. (1987).[5] M.V. Maksyuta, Proceedings of the IV Int. conf. Electronics and applied physics, Oct. (2008).
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15
Realistic 3D implementation of electrostatic elements
for low energy machines
V. Rodin1,2, J. R. Hunt1,2, J. Resta-Lopez1,2, B. Veglia1,2
and C. P. Welsch1,2
1. The University of Liverpool, Liverpool, United Kingdom2. The Cockcroft Institute, Sci-Tech Daresbury, Warrington, United Kingdom
Novel antimatter experiments at CERN require high intensity, low energy (<100 keV) antiproton beams.Each experiment has a set of desirable beam parameters. To achieve this, and obtain the greatestefficiency, transfer lines will be based on electrostatic optics. Unfortunately, only a small amount ofsimulation codes allow realistic and flexible implementation of such elements.In this contribution, methods for accurately creating and tracking through electrostatic optical elementsare presented, utilising a combination of a modified version of G4Beamline [1] and finite element methods.To validate our approaches the transfer line from the ELENA ring to the ALPHA experiment was chosenas a basis for particle tracking studies. A range of approaches to modelling the electrostatic elementswere explored, ranging from simple field expressions, to the complex field maps used in the final model.An investigation into the achievable beam quality at ALPHA is presented.
References
[1] Tom Roberts, G4Beamline Simulation Program for Matter-Dominated Beamlines, PAC07 Proceedings(2017)
79
16
High intensity positron beam production for the
GBAR experiment
Barbara Latacz on behalf of the GBAR collaboration1. (DRF) Irfu/DPhP CEA-Saclay
The main goal of the GBAR (Gravitational Behaviour of Anihydrogen at Rest) experiment is to test theweak equivalence principle for antimatter using H [1]. In order to perform that complex experiment,ultracold antihydrogen atoms (≈ 10µK) are needed. As it is impossible to cool down neutrals to requiredtemperature, GBAR will produce the antihydrogen ion and measure its free fall time after detachmentof an extra positron.The antihydrogen ion production for the GBAR collaboration is made through the charge exchangereactions with positronium Ps, p+Ps∗ → H∗+ e−−and H∗+Ps∗ → H+ + e−. The main ingredient forthose reactions is a high density positronium cloud, which can be produced by implanting high intensitypositron beam into porous silica target.The GBAR team designed a positron source based on a 9 MeV electron linac. The final linac structureis currently being commissioned and will reach 300 mA peak current with 300 Hz repetition rate. In thisposter the scheme of the positron production line and the newest results will be presented.
References
[1] G. Chardin et al., Proposal to measure the Gravitational Behaviour of Antihydrogen at Rest GBARhttps://cds.cern.ch/record/1386684/files/SPSC-P-342.pdf (2011).
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17
Sympathetic cooling of H+
Thomas Louvradoux1, Johannes Heinrich1, Nicolas Sillitoe1,Albane Douillet1,2, Jean-Philippe Karr1,2, Laurent Hilico1,2, Paul
Indelicato1, Jean-Pierre Likforman3, Samuel Guibal3, LucaGuidoni3
1 Laboratoire Kastler Brossel, Sorbonne Universite, ENS-Universite PSL, CNRS, Collge de France, 4place Jussieu, 75000 Paris.
2 Universite d’Evry val d’Essonne, bd. F. Mitterrand, 91000 EVRY3 Laboratoire Materiaux et Phenomenes Quantiques, Universite Paris Diderot, CNRS UMR 7162,
Sorbonne Paris Cite, France
One important step in the GBAR project is sympathetic cooling of the H+
ion by laser cooled Be+ ionsfrom eV energies down to µeV (thousands of K down to mK). We follow several approaches to tackle thisissue.
The first one relies on numerical simulations taking into account the RF trapping field of the Paul trapand the exact coulomb interactions between the ions. It shows that an mixed specie ion cloud containingcontaining Be+ and HD+ is much more efficient than a pure Be+ ion cloud because mechanical couplingsare much better with a mass ratio of three rather than with a mass ratio of 9.
The second approach is experimental and uses on a Sr+/Be+ mixed ion cloud having a comparable 86/9mass ratio. Both ion species can be imaged on a CCD camera, which allow for monitoring the sympa-thetic cooling dynamics of the light ion (Be+) by the heavy one (Sr+).
The H+
ion can be easily photodetached by the Be+ cooling light at 313 nm. We show that laser cool-ing to low temperature and Coulomb crystallisation are also effective with a donought (Laguerre-Gauss)mode.
[1] L. Hilico, J.-Ph. Karr, A. Douillet, P. Indelicato, S. Wolf, F. Schmidt Kaler, Preparing single ultra-coldantihydrogen atoms for free-fall in GBAR Int. J. Mod. Phys. Conf. Ser. 30, 1460269
[2] N. Sillitoe, J.-Ph. Karr, J. Heinrich, T. Louvradoux, A. Douillet, L. Hilico H+
Sympathetic CoolingSimulations with a Variable Time Step JPS Conf. Proc. 18, 011014
81
18
3D-imaging of antimatter annihilation using the
ASACUSA Micromegas tracker
V. Mackel1, B. Radics2∗, C. Amsler1, H. Breuker3, M. Diermaier1,P. Dupre2, M. Fleck1, H. Higaki4, Y. Kanai5, T. Kobayashi6,
B. Kolbinger1, M. Leali6, C. Malbrunot3, V. Mascagna6,O. Massiczek1, Y. Matsuda7, D. Murtagh1, Y. Nagata8,
C. Sauerzopf1, M.C. Simon1, M. Tajima5, S. Ulmer2, N. Kuroda7,L. Venturelli6, E. Widmann1, Y. Yamazaki2, J. Zmeskal1
1. Stefan Meyer Institute, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria2. Ulmer Fundamental Symmetry Laboratory, RIKEN, Saitama 351-0198, Japan
3. CERN 1211, Geneva 23, Switzerland4. Graduate School of Advanced Science of Matter, Hiroshima University, Hiroshima 739-8530, Japan
5. Nishina Center for Accelerator-Based Science, RIKEN, Saitama 351-0198, Japan6. Dipartimento di Ingegneria dell’Informazione, Universita di Brescia, I-25133 Brescia, Italy and
Istituto Nazionale di Fisica Nucleare, Sez. di Pavia, I-27100 Pavia, Italy7. Institute of Physics, University of Tokyo, Tokyo 153-8902, Japan
8. Department of Physics, Tokyo University of Science, Tokyo 162-8601, Japan
The ASACUSA collaboration aims at measuring the ground state hyperfine splitting of antihydrogen forprobing fundamental symmetries. A cryogenic double cusp trap for mixing antiprotons and positronsserves as an antihydrogen source for inflight spectroscopy [1,2]. In order to be able to monitor theantihydrogen formation process, the ASACUSA Micromegas Tracking (AMT) detector was installedfor detecting and reconstructing the antiproton and antihydrogen annihilations in the trap in threedimensions [3].The AMT detector consists out of two curved gaseous detector layers using micromegas technology [4].The layers form two half cylinders and are mounted concentrically with the trap electrodes on the upperside of the vacuum chamber containing the trap. A single, full-cylinder layer of plastic scintillator betweenthe two Micromegas layers provides fast signals for triggering the read ou- of the micromegas channels.As an active gas, a mixture of argon (90%) and isobutane (10%) is used. The drift region has a heightof 3 mm, while the amplification region has a height of 128µm. A relatively high drift voltage of 1600 Vand an amplification potential of 460 V are applied, which sufficiently reduce the influence of the Lorentzforce on the drift electrons due to the magnetic field of the trap.Besides explaining the AMT detector in detail and describing the event reconstruction algorithm, wepresent annihilation data recorded during the 2016 beam time. Annihilation data from antiprotons showthat the AMT detector is able to discriminate between annihilations on-axis and on the inner electrodewalls of the trap [5]. The latter type of events are the primary signal candidates to be antihydrogenatoms.
References
[1] E. Widmann et al., Hyperfine Interactions 215, 1 (2013)[2] N. Kuroda et al., Nature Communications 5 3089 (2014)[3] B. Radics et al., Rev. Sci. Instrum. 86, 083304 (2015)[4] Y. Giomataris et al., Instr. Meth. A 376 (1996)[5] V. Mackel et al., submitted to NIMB
∗Current address: Institute for Particle Physics, ETH Zurich, Zurich CH-8093, Switzerland82
19
Casimir-Polder shifts on quantum levitation states
P.-P. Crepin1, G. Dufour1,2, R. Guerout1, A. Lambrecht1 and S.Reynaud1
1. Laboratoire Kastler Brossel, UPMC-Sorbonne Universites, CNRS, ENS-PSL Research University,College de France, Jussieu case 74, F-75252 Paris, France.
2. Physikalisches Institut, Albert-Ludwigs-Universitat Freiburg, Hermann-Herder-Straße 3, D-79104,Freiburg, Germany
An ultracold atom above a horizontal mirror experiences quantum reflection from the attractive Casimir-Polder interaction, which holds it against gravity and leads to quantum levitation states. We analyze thissystem by using a Liouville transformation of the Schrodinger equation and a Langer coordinate adaptedto problems with a classical turning point. Reflection on the Casimir-Polder attractive well is replacedby reflection on a repulsive wall and the problem is then viewed as an ultracold atom trapped inside acavity with gravity and Casimir-Polder potentials acting respectively as top and bottom mirrors. Wecalculate numerically Casimir-Polder shifts of the energies of the cavity resonances and propose a newapproximate treatment which is precise enough to discuss spectroscopy experiments aiming at tests ofthe weak equivalence principle on antihydrogen. We also discuss the lifetimes by calculating complexenergies associated with cavity resonances.
0 1 2 3 4 5 6 7 8z (`g)
−2
0
2
4
6
8
V,E
(εg)
0.00 0.05 0.10
−20
−10
0
−2 0 2 4 6 8z
−2
0
2
4
6
8
V,E
−0.1 0.0 0.1 0.2
0
200
400
600
Figure 1: Potential landscape for antihydrogen atom in the combined gravity and CP potentials,before (on the left) and after (on the right) a Liouville transformation. Color lines represent theenergy levels.
83
20
Intensity measurement of the Antiproton Decelerator
beam using a Cryogenic Current Comparator with
nano-ampere resolution
M. Fernandes1,2; D. Alves2; T. Koettig2; A. Lees2; M.Schwickert3; T. Stohlker4, J. Tan2; C.P. Welsch1;
1. The University of Liverpool, Liverpool, U.K.2. European Organization for Nuclear Research (CERN), Geneva, Switzerland
3. GSI Helmholtzzentrum fur Schwerionenforschung GmbH (GSI), Darmstadt, Germany4. Friedrich-Schiller-Universitat, Jena, Germany
The Antiproton Decelerator (AD) and Extra Low ENergy Antiproton (ELENA) rings at CERN deceleratebeams containing 107 antiprotons. These low-intensity particle beams are particularly challenging fornon-perturbative beam diagnostics due to the small amplitude of the induced electromagnetic fields.However, an absolute intensity measurement of the circulating beam is essential to monitor the operationalefficiency, reduce beam commissioning times and to provide important calibration data for the antimatterexperiments. This paper reviews the design of an operational Cryogenic Current Comparator (CCC)based on Superconducting QUantum Interference Device (SQUID) for current and intensity monitoringin the AD. Such a system has been operational throughout 2017, relying on a stand-alone liquid heliumcryostat with cooling power provided by a pulse-tube cryocooler. The performance of the intensity beamdiagnostic and of the cryogenic system is also presented, confirming a resolution in the nano-ampererange, with both bunched and coasting beam.
References
84
21
Feasibility study of the measurement of annihilation
photons polarization with the J-PET detector
Nikodem KrawczykFaculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, S. Lojasiewicza
11, 30-348 Krakow, Poland
J-PET is a prototype of the positron emission tomograph built from plastic scintillators [1,2,3] in whichphotons interact predominantly via Compton effect. Thanks to Klein-Nishina formula polarization may beestimated by measurement of the direction of primary and scattered photons. Knowledge about polariza-tion of photons originating from the decay of positronium allows us to study various physical phenomenasuch as quantum entanglement [4] and discrete symmetries breaking [5]. The poster will present resultsof simulations showing the possibilities of the J-PET detector for the polarisation determination of the511 keV photons.
References
[1] P. Moskal et al., Nucl.Med.Rev. 15 (2012) C81-C84[2] P. Moskal et al., Radiotheraphy and Oncology 110 (2014) S69[3] P. Moskal et al. Nucl.Instrum.Meth. A764 (2014)[4] B.C. Hiesmayr, P. Moskal, Nature: Scientific Reports 7 (2017)[5] P. Moskal et al., Acta Phys. Polon. B 47, 537 (2016)
85
22
Simulations of the formation of trappable
antihydrogen
Svante Jonsell1 and Mike Charlton2
1. Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden2. Department of Physics, College of Science, Swansea University, Swansea SA2 8PP, UK
We simulate the formation of antihydrogen through three-body recombination when antiprotons areinjected into a positron plasma, which is trapped in a Penning trap. Here, we focus on the fraction thatfulfil the conditions necessary for confinement of anti-atoms in a magnetic minimum trap. Our methodis based on classical trajectories of positrons and antiprotons, and has been explained in detail in [1].Antihydrogen atoms formed inside a positron plasma are followed until they leave the plasma radially.At this point it is determined wether the antiatom could be magnetically trapped. For this to be the caseit has to fulfil three conditions:
1. It has to be bound and stable. This is tested by simulating the influence of a 10 V/cm axial electricfield for the duration of 1 µs. If the antiatom is still bound after this time, we classify it as a stableantihydrogen.
2. It has to be in a low-field seeking state. That is, its orbital angular momentum must be antiparallelto the magnetic field.
3. Its kinetic energy must be less than 2 Kelvin. This is larger than the depth of current magnetictraps, but was chosen to get sufficient statistics within a reasonable time. If one assumes that theinitially formed antiatoms follow a thermal distribution with temperature � 2 Kelvin, one caneasily scale our results to lower trap depths.
In our simulations we have used the positron temperature, the positron density, and the trap radius wherethe antiprotons are injected as parameters.Trapping fractions of around 10−4 are found under conditions similar to those used in recent experiments,and in reasonable accord with their results. We find that collisional effects play a beneficial role via aredistribution of the antihydrogen magnetic moment, allowing enhancements of the yield of low-fieldseeking states that are amenable to trapping. We also find unexpected features in the distribution ofbinding energies.
References
[1] S Jonsell, M Charlton and D P van der Werf, Journal of Physics B: At. Mol. Opt. Phys. 49, 134004(2016).
86
23
Lifetime of Magnetically Trapped Antihydrogen in
ALPHA
Andrea Capra1 for the ALPHA collaboration1. TRIUMF, 4004 Wesbrook Mall, Vancouver BC V6T 2A3, Canada
How long antihydrogen atoms linger in the ALPHA magnetic trap is an important characteristics ofthe ALPHA apparatus. The initial trapping experiments in 2010 [1] were conducted with 38 detectedantiatoms confined for 172 ms and in 2011 [2] with seven for 1000 s. Long confinement times are necessaryto perform detailed frequency scans during spectroscopic measurements. An analysis carried out, usingmachine learning methods, on more than 1000 antiatoms confined for several hours in the ALPHA-2 magnetic trap, yields a preliminary lower limit to the lifetime of 66 hours. Hence this observationsuggests that the measured confinement time of antihydrogen is extended by more than two orders ofmagnitude.
References
[1] G. B. Andresen et al. (ALPHA collaboration), Nature 468, 673-676 (2010)[2] G. B. Andresen et al. (ALPHA collaboration), Nature Phys. 7, 558-564 (2011)
87
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Magnetometry Techniques for Gravitational
Measurements of Antihydrogen with ALPHA-g
N. Evetts1 and the ALPHA collaboration1. Department of Physics and Astronomy, University of British Columbia, Vancouver BC, Canada V6T
1Z1.
The ALPHA collaboration is constructing a new apparatus (ALPHA-g) to measure matter-antimattergravitational interactions with magnetically trapped antihydrogen. The magnetic forces that are usedfor antiatom containment will dominate over the gravitational forces we hope to measure. In orderto distinguish between these two types of forces experienced by the antihydrogen atoms, custom, highprecision magnetometry methods need to be developed. This poster will discuss techniques borrowedfrom the fields of non-neutral plasmas and nuclear magnetic resonance. These methods are deployed intandem and result in magnetic field sensors with precisions of about 1 part in 10,000. The implicationsof this precision on antihydrogen gravity measurements are considered. Factors limiting our magneticfield measurements are also discussed, as well as directions for improvement.
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Development of the Radial Time Projection Chamber
for the ALPHA-g antimatter gravity experiment
L. Martin1, P.-A. Amaudruz1, D. Bishop1, A. Capra1, M.Constable1, W. Faszer1, S. Freeman1, M.C. Fujiwara1, D.R.
Gill1, M. Grant1, R. Henderson1, L. Kurchaninov1, P. Lu1, N.Massacret1, M. Mathers2, J.T.K. McKenna1, S. Menary2, K.Olchanski1, K. Ong1, L. Paulson1, F. Retiere1, B. Shaw1, D.
Starko2, J. Thompson2 and E. Zaid1
1. TRIUMF, Vancouver BC Canada V6T 2A32. Department of Physics and Astronomy, York University, Toronto ON Canada, M3J 1P3
Antimatter is believed to be affected by gravity in exactly the same way as ordinary matter for a varietyof good reasons [1], however this has never been measured directly. This will be tested by the ALPHA-gproject, which uses a new vertical antihydrogen trap based on the previous ALPHA design (AntihydrogenLaser Physics Apparatus, the first experiment to trap antihydrogen in 2010 [2]). As in previous ALPHAexperiments, the trapped antihydrogen is detected via its charged annihilation products after switchingoff the trap. In order to be sensitive to small gravitational effects, the setup extends more than 2metres in the vertical direction, requiring the particle detection system to cover a large volume with goodtracking accuracy. The design chosen to replace the previous experiments’ silicon strip detectors is aradial time-projection-chamber (rTPC) filled with an Argon/CO2 gas mixture.Following successful tests with a smaller prototype, the full-scale chamber was completed in early 2018and the basic functionality of the detector was established. Soon after, initial tests with cosmic rays leadto the observation of tracks due to charged particles.The specific parameters of the chamber together with the necessity to observe minimum-ionizing parti-cles leads to relatively complex signals on the detector electrodes, which have to be deconvolved in aniterative process. The deconvolution algorithm and its results for both simulated and prototype signalsare presented.
References
[1] M. M. Nieto and J. T. Goldman, Phys. Rep. 205, 221-281 (1991).[2] G. B. Andresen et al., Nature 7324, 673 (2010).
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Magnetic Trap Design in ALPHA-g
Chukman So1 for the ALPHA collaboration1. TRIUMF, 4004 Wesbrook Mall, Vancouver BC V6T 2A3, Canada
The weight of antimatter is a crucial missing measurement in our picture of the natural world. It isimportant in two ways: (1) The predominance of matter created in the Big Bang demands some formof mismatch in properties between matter and antimatter. Many experiments have sensitively comparedtheir charge, magnetic moment, nuclear bonding and decay behaviour, yet no significant mismatch hasbeen found to date to explain the cosmic matter dominance. One of the last unexplored domains isgravitational behaviour. (2) Our understanding of the subatomic world is wholly incompatible withGeneral Relativity, the dominant phenomenon on astronomical scales. New ideas on a unified theory onatomic and gravitational interactions may require antimatter to respond uniquely to gravity. Measuringsuch behaviour experimentally will provide vital evidence to accept or reject these ideas, and further thedevelopment of a unified view of nature.Experimentally, weighing antimatter has been difficult because electrical influences on the charged, en-ergetic antiparticles commonly created in accelerators massively overwhelm their gravitational response.Their short life in these machines also leaves no time for observation. The antihydrogen trapping tech-nology developed by the world-leading ALPHA collaboration has, however, completely altered this pic-ture, by generating antimatter that has low energy, long lifetime and immunity to electric forces. Thenew ALPHA-g experiment is designed to leverage this new technology, and weigh antimatter by lettingantiatoms escape through the bottom and top of a tall magnetic confinement system. By precisely con-trolling the magnetic field of the openings, the escape bias induced by gravity can infer antihydrogenweight to within 1%. This constitutes the most sensitive antimatter gravity measurement ever made, anda significant breakthrough in subatomic and fundamental physics.This poster presentation outlines the design of the magnetic confinement and measurement system ofALPHA-g, the challenges to achieving magnetic control necessary for a 1% precision in antihydrogengravity, and the techniques developed to mitigate them.
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UPMC conference center
UPMC, 4 place Jussieu75005 ParisMetro line 7 or line 10 Jussieu
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Conference Dinner
Thursday 15th of March, 19:30
La Coupole, 102 rue du Montparnasse, 75014 ParisMetro 4 station VavinMetro 6 station Raspail
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Local visits
Collection de minerauxhttp://www.collection-mineraux.upmc.fr/fr/index.html
Monday, Wednesday, Thursday, Friday: 13:00-18:00, Tuesday: closedrate: 6 e
Patrimoine Artistiquehttp://www.patrimoine-artistique.upmc.fr/fr/index.html
Jean Arp, Franois Beaudin, Alexander Calder, Roger Chapelain-Midy, Jacques Despierre, Lon Gischia,Jacques Lagrange, Pierre Manoli, Andr Planson, Jean Souverbie, Franois Stahly, Adam Steiner,
Raymond Subes, Victor Vasarely
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